Nasal gas delivery system and method for use thereof

ABSTRACT

A gas administering method for administering gas to an airway of a patient having a nasal vestibule and for use with a gas administering apparatus comprises a primary gas source that is operable to provide gas and a nasal vestibular portion arranged so as to receive the gas from the primary gas source. Further, the nasal vestibular portion is capable of releasing the primary gas into the nasal vestibule. The method comprises inserting the nasal vestibular portion into the nasal vestibule, forming a seal between the nasal vestibular portion and an inner surface of the nasal vestibule, administering an amount of a gas from the primary gas source at a constant flow rate into the nasal vestibule via the nasal vestibular portion, and administering an anesthetic to the patient. The anesthetic induces depression of a portion of the nervous system of the patient. Furthermore, the seal promotes airway pressure buildup that is sufficient to prevent obstruction of the airway during depression of at least a portion of the nervous system and prevents escape of the gas from between the nasal vestibule and the nasal vestibular portion.

This is a Continuation-In-Part Application of Utility Application havingSer. No. 10/639,474, filed Aug. 13, 2003 now U.S. Pat. No. 6,848,446,which is a Continuation-In-Part Application of Utility Applicationhaving Ser. No. 10/183,498, filed Jun. 28, 2002 now U.S. Pat. No.6,637,434, which is a Continuation-In-Part Application of Utilityapplication having Ser. No. 09/430,038, filed Oct. 29, 1999 now U.S.Pat. No. 6,561,193, which claims priority on Provisional Application60/106,271, filed Oct. 30, 1998. The present Application additionallyclaims priority to Provisional Application having Ser. No. 60/402,713,filed Aug. 13, 2002 and to Provisional Application having Ser. No.60/442,065, filed Jan. 24, 2003, to Provisional Application having Ser.No. 60/508,872, filed Oct. 7, 2003, to Provisional Application havingSer. No. 60/536,997, filed Jan. 20, 2004, to Provisional Applicationhaving Ser. No. 60/570,116, filed May 12, 2004, and to ProvisionalApplication having Ser. No. 60/591,875, filed Jul. 29, 2004. The entiredisclosures of applications having Ser. Nos. 10/639,474, 10/183,498,09/430,038, 60/106,271, 60/402,713, 60/442,065, 60/508,872, 60/536,997,60/570,116, and 60/591,875 are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a gas delivery apparatus foradministering a gas to a patient during surgery, and more particularlyfor delivering anesthetic to a patient during surgery.

During surgical procedures, there is a need to anesthetize a patient inorder to eliminate, or at least reduce: pain associated with theprocedure; and movement of the patient during the procedure. Anesthesiais considered a drug-induced depression of at least a portion of nervoussystem, or portion thereof, of the patient.

In the sequence of events of drug-induced depression of the centralnervous system, there occurs a level of depression that allows themuscles of the pharynx (e.g. the tongue) to relax causing soft-tissuestructures to collapse into and obstruct the airway. This happens at anearlier stage than that at which the muscles of respiration (e.g. thediaphragm) cease to function. In other words, a condition known as“obstructive apnea,” where the diaphragm is struggling to pull airthrough an obstruction of the upper airway occurs before the diaphragmitself ceases to function (“central apnea”). In this sequentialdepression of the central nervous system, death occurs from Asphyxiabefore the drug itself can produce complete depression of the nervoussystem.

Similarly, even partial obstruction will cause disastrous consequencesof an immediate and/or long-term nature. For example the resultinghypoxia (i.e., oxygen deficiency) will cause a reflex constriction ofblood vessels in the lungs leading to pulmonary hypertension and theright portion of the heart's failure to pump blood efficiently throughthe lungs to the left portion of the heart. Accordingly, the heart isunduly taxed and the circulatory reserves of well oxygenated blood areimpaired. The resulting hypercarbia (i.e., the abnormal accumulation ofcarbon dioxide) will cause acidosis (i.e., the accumulation of acid)leading to depression of organ systems. The central nervous system, forinstance, will become progressively depressed to a deep coma directlyrelated to the level of retained carbon dioxide. Further, the resultingstronger negative intra-thoracic pressure, that is generated by thebellows action of the diaphragm pulling on the chest cavity as thepatient attempts to draw air through an obstructed upper airway, leadsto two problems. First, a greater negative intra-pulmonary pressure(i.e., the negative pressure transmitted to inside the lungs) dilatessmall blood vessels to cause excessive blood flow around the alveoli(i.e., the small air sacs). Concurrently, a vacuum is created whichsucks fluid out of the circulation to fill the void generated within thealveoli. Hypoxia ensues, first, from the mismatch of circulation toventilation and, then, rapidly deteriorates as pulmonary edema (i.e.,fluid in the air sacs) worsens. Second, a greater negative pressure inthe chest cavity is also transmitted to the esophagus. An esophagealpressure more negative, relative to the pressure within the stomach,establishes a pressure gradient which favors the reflux of gastric acidup the esophagus where it will bum pharyngeal structures and, ifaspirated into the lungs, will cause severe and, sometimes, fataldestruction of lung tissue.

An upper airway obstruction occurs upon the induction of almost everygeneral anesthetic and is a frequent occurrence during theadministration of heavy sedation for procedures done nominally under“local anesthesia with sedation.” Under most conditions, the treatmentis so routine as to be taken for granted by practitioners skilled inairway management.

The condition which has been called SNOR (Syndrome of NarcogenicObstructive Respiration) is a common occurrence in the practice ofanesthesia. Drugs, which induce depression of the central nervous systemto prevent the perception of pain, concurrently induce upper airwayobstruction. Many airway devices and methods are used to alleviate theproblem. One method, not yet widely practiced, involves the delivery ofair and/or oxygen and anesthetic gases under positive pressure throughthe nose of the patient to prevent airway obstruction in a fashion verysimilar to that used in the home therapy of Obstructive Sleep Apnea(OSA). In SNOR, however, a nasal appliance is connected to any ofseveral commonly-employed anesthesia circuits of tubing which areconnected to anesthesia machines and/or other sources of oxygen, air andanesthetic gases. Gas flows can be used to generate the relatively lowpressures through the nose that will usually relieve upper airwayobstruction and allow spontaneous respiration.

Another common occurrence in the practice of anesthesia, in addition toSNOR, is the use of 100% oxygen or oxygen mixed with nitrous oxide.Nitrous oxide, itself, supports combustion and any combination of thetwo gases, when allowed onto the surgical field, will find plenty offuel (e.g., plastic and paper drapes, hair, etc.) and ready sources ofignition (e.g., electro-cautery, LASER, fiberoptic lights, etc.). Thispotential joining of the three sides of the “fire triangle” can resultin a chain reaction that is often explosive in its evolution and is thecause of, “. . . approximately 100 surgical fires each year, resultingin up to 20 serious injuries and one or two patient deaths annually.”(SENTINEL EVENT ALERT, Jun. 24, 2003, from the Joint Commission onAccreditation of Healthcare Organizations)

Other problems are associated with the use of high concentrations ofoxygen and nitrous oxide. High oxygen concentrations over many hours caninduce severe inflammation of the lungs and respiratory distress.Further, without nitrogen to keep them inflated, 100% oxygen is rapidlyabsorbed from under-ventilated alveoli, allowing them to collapsecausing “absorption hypoxia” and a predisposition to pneumonia. Stillfurther, nitrous oxide diffuses so rapidly from the circulation into thealveoli at the end of anesthesia that adequate oxygen can be preventedfrom entering the alveoli.

The solution to the above problems is as simple as eliminating nitrousoxide, the use of which is more traditional than helpful, and adding airto all anesthetic gases. The nitrogen in air dilutes the oxygen andabsorbs heat to impede the chain reaction of combustion. The realproblem is that many anesthesia settings do not have the capability todeliver air to the mixture of anesthesia gases. Operating rooms oftenhave not been piped for air and many anesthesia machines are notdesigned to deliver air. Moreover, compressed “medical air” isexpensive. Manual support of the airway such as with an invasiveendotracheal tube, application of a face mask over the mouth and noseand various other airway devices are employed, often with supplementaloxygen.

However, the use of a face mask or an endotracheal tube during surgicalprocedures has many drawbacks. The standard face mask places pressure onthe chin and tends to collapse soft-tissue structures of the oropharynx.Additionally, air pressure that is applied through the face mask tendsto equalize through the nose and the mouth, and therefore it can becounter-productive to the supporting of soft tissue to open the airway.Further, using a face mask usually requires one or two additionalmaneuvers, for example manual support of the chin, the insertion of anoral airway, etc., in order to remedy the problem. None of the invasiveairway-support devices currently used in conventional anesthesiapractice can be inserted in the conscious patient without causingsignificant discomfort and/or physiological disturbance.

Furthermore, recent advances in cosmetic surgery have made airwaymanagement significantly more challenging and have caused practitionersto accept conditions having a reduced margin of safety for theirpatients. In particular, laser procedures on the face are requiringheavier sedation leading more often to respiratory depression andobstruction while, at the same time, the increased fire hazard restrictsthe use of oxygen.

Obstructive Sleep Apnea (OSA), a syndrome defined in the early 1980's,is similar to drug-induced obstructive apnea in anatomy and treatment.The treatment of OSA has demonstrated that upper airway obstructionoccurring during the sleep of afflicted patients can be relieved by theapplication of positive pressure through the nose alone. OSA differsfrom drug-induced obstructive apnea in that it is not drug-induced.Further, OSA typically does not have acutely disastrous consequences,but rather has long-term ill-effects and is a chronic condition.

A conventional method for treating a form of OSA is to provide acontinuous positive airway pressure (C-PAP) through the nose in order toprevent an upper airway obstruction. Nasal masks are used, as are nasalinsert devices. InnoMed Technologies, for instance, provides a devicecalled NasalAire used to treat obstructive sleep apnea. The deviceincludes conical shaped nasal inserts connected to gas delivery tubeswhich are connected to an air delivery system. A C-PAP generator isincluded, which automatically increases and decreases air flow rate tomaintain a continuos positive airway pressure. Furthermore, the deviceincludes vent holes for venting CO₂ from the exhaling user.

FIG. 1 illustrates a conventional system for treating sleep inducedapnea by providing a constant positive airway pressure through the nose.As depicted in the figure, the patient 104 is fitted with tubing 102.The tubing 102 receives airflow from a C-PAP machine and administers theairflow to the nose of the patient by tube branches 106. An airflowdelivery device 108, having nasal inserts 110 is placed such that nasalinserts 110 are disposed within the nasal vestibules 114 of patient 104.Airflow delivery device 108 additionally includes ventilation holes 112,which provide ventilation for CO₂ from the user during expiration.Examples of such devices are disclosed in U.S. Pat. No. 5,533,506 toWood, U.S. Pat. No. 4,702,832 to Tremble et al, and U.S. Pat. No.5,134,995 to Gruenke et al., the entire disclosures of which areincorporated herein by reference.

What is needed is a method and apparatus for preventing complete airwayobstruction of a patient when the patient is deeply sedated afterinduction of anesthesia.

What is additionally needed is a method and apparatus for enabling apatient to adequately respire at surgical levels of anesthesia withoutan invasive airway and manual or mechanized ventilation.

What is additionally needed is a method and apparatus forcost-effectively adding air to the anesthetic gasses for reducing therisk of combustion in the surgical field when using cautery or laserdevices.

What is additionally needed is a method and apparatus for preventingleakage of the anesthesia to the operating room.

What is additionally needed is a method and apparatus for moreaccurately monitoring spontaneous respirations in a pressurized system.

What is additionally needed is a method and apparatus for preventing anairflow generator from excessively pressurizing an anesthesia circuit.

What is additionally needed is an apparatus that is: operablyconnectable to an existing anesthetic delivery apparatus; operable toprevent complete airway obstruction of a patient when the patient isdeeply sedated after induction of anesthesia; and operable to enable apatient to adequately respire at surgical levels of anesthesia withoutan invasive airway and manual or mechanized ventilation.

What is additionally needed is an inexpensive method of adding air tothe various breathing circuits used in the operating room, recovery roomand other critical care areas. An airflow generator which does not storeair in a compression tank, but immediately delivers it to the patient,could provide the same ambient air that the patient would be breathingon his own, if not being treated, and would draw from the same safe airsupply breathed by those healthcare providers in attendance. Moreover,if a filter were attached to the airflow generator then the patientwould, in theory, be breathing air more pure than ambient air.

As opposed to a conventional continuous-pressure airflow generator(i.e.,“C-PAP machine”), what is additionally needed is an airflowgenerator operable to generate a constant flow rate and allow the airwaypressure to vary.

What is additionally needed, is a device (adapter) which could convert astandard “C-PAP Machine” from continuous-pressure air delivery tocontinuous-flow air delivery.

What is needed, is a reliable continuous breath-by-breath monitor of thebreathing circuit and the patency of the upper airway of the patient. Astethoscope designed to fit in-line with the tubing of the breathingcircuit would transmit the unique combined sounds of airflow through thecircuit and upper airway of the patient. Such a stethoscope would givethe earliest warning of impending airway obstruction and allowcorrective action to be taken within a breath of discovery withimmediate feedback as to the effectiveness of the remedy.

What is further needed is a simple and inexpensive mechanical monitor ofinspiratory flow.

If the patient is intubated for general anesthesia, at the end of thesurgical procedure, C-PAP may be applied as the patent is extubatedrelatively deep and unreactive to the endotracial tube. This allows thepatient to awaken without the upper airway obstruction and the coughingand gagging that often accompanies emergence from endotracialanesthesia. In so doing, evasive airways are avoided, the functionalresidual capacity is optimize, atelectasis is prevented and eliminationof the anesthetic vapors is promoted. Accordingly, what is needed is away of continuously supplying C-PAP to a patient recovering from generalanesthesia: from the time the anesthesia is turned off in the operatingroom, during transport to the recovery room; and through the entirerecovery phase until the patient is well awake.

SUMMARY OF THE INVENTION

It is the object of this invention to provide a method and apparatusthat may comfortably be applied to the conscious patient prior to theinduction of anesthesia to prevent airway obstruction and maintainoxygenation after the patient has become unconscious under the influenceof anesthesia.

It is another object of this invention to enable a patient to adequatelyrespire at surgical levels of anesthesia without an invasive airway andmanual or mechanized ventilation.

It is another object of this invention to cost-effectively add air tothe anesthetic gasses for reducing the risk of combustion in thesurgical field when using cautery or laser devices.

It is another object of this invention to prevent leakage of theanesthesia to the operating room.

It is another object of this invention to more accurately monitorspontaneous respirations in a pressurized system.

It is another object of this invention to prevent an airflow generatorfrom excessively pressurizing an anesthesia circuit.

It is another object of this invention to provide an airflow generatoroperable to generate a constant flow rate and allow the airway pressureto vary. Such a constant flow rate airflow generator would have severaladvantages in critical care settings. A constant rate of airflow wouldallow the reservoir bag of the anesthesia circuit to fluctuate in theusual manner, thereby establishing a simple and reliable monitor ofrespirations in critical care situations. Accordingly, adjustment of therate of constant flow, may be used to establish a fluctuating positivepressure in the breathing circuit, always positive, but more positive onexpiration and less positive on inspiration. Such a pattern wouldpromote venous return to the heart by the bellows-like action of the“thoracic pump.” Further, the constant flow would better allowcapnographic monitoring of respirations, the monitoring of which isimpeded by the excessive flows generated by C-PAP machines whichrestrict carbon dioxide from entering the breathing circuit.Accordingly, it follows that a greater volume of humidified expiratoryair courses through the breathing circuit. This moisture can be capturedby a “heat and moisture exchange” filter and used to humidify theinspiratory air delivered to the patient. Such a system would be ofbenefit to the OSA patient at home where the C-PAP machine is known tocause dry and sore throats.

It is another object of this invention to provide an airflow generator,for example, a portable or battery operated constant airflow generator,could be used to transport patients. After anesthesia, for example, theairflow generator could remain attached to the breathing circuit whilethe patient is being transported to the recovery room and, then, left inplace while the patient is recovering. The advantages of this include:a) the positive pressure would optimize expansion of the patient's lungsduring a time in which the patient typically hypoventilates; b) thepositive pressure would continue to prevent obstruction and thetriggering of larygospasm which too often occurs during emergence fromanesthesia; c) the augmented respiratory flows would facilitate thewashing-out of anesthesia gases from the lungs; and d) air supplied tothe lungs under positive pressure corrects hypoxia from thehypoventilation which can lead to “absorption atelectasis” and pneumoniaif treated only by administering oxygen.

Not only would ambient air be cost-free and inexhaustible, but anydesired level of oxygen enrichment could be achieved with the additionof only a small fraction of the oxygen used in conventional systems.Therefore, such an airflow generator would provide an economic advantageof the more costly oxygen delivery systems.

The constant-flow airflow generator could be used to add an exact amountof air to a conventional anesthesia system, thereby allowing a preciseadjustment of the anesthesia gas vaporizer to deliver any desiredend-concentration of anesthetic gas.

The constant-flow airflow generator could, itself, provide the carriergas to an anesthesia vaporizer of the “draw-over” type and, thereby,eliminate the need for a standard anesthesia machine. Such a system,especially if combined with battery power and an oxygen concentrator,would eliminate the need for tanks of compressed gases and be relatively“free-standing” and more portable than existing systems.

It is another object of this invention to provide a device (adapter)which could convert a standard “C-PAP Machine” from continuous-pressureair delivery device to continuous-flow air delivery device. If, first,the C-PAP machine were to be set at a fixed pressure, then, the airout-put could be directed through a variable-resistance orifice toproduce an adjustable fixed flow. Whereas a standard “C-PAP Machine” isdesigned to meet the high flow rates of inspiration by pumping more airto maintain a constant pressure, the adapter system would require that areservoir bag be provided to meet the flow demands of inspiration.Nevertheless, in anesthesia and critical care breathing circuits, thiscan be used to advantage, as discussed previously.

It is another object of this invention to provide a reliable continuousbreath-by-breath monitor of the breathing circuit and the patency of theupper airway of the patient. A stethoscope designed to fit in-line withthe tubing of the breathing circuit would transmit the unique combinedsounds of airflow through the circuit and upper airway of the patient.Such a stethoscope would give the earliest warning of impending airwayobstruction and allow corrective action to be taken within a breath ofdiscovery with immediate feedback as to the effectiveness of the remedy.

It is another object of this invention to provide a simple andinexpensive mechanical monitor of inspiratory flow.

It is another object of this invention to provide a system forcontinuously supplying C-PAP to a patient recovering from generalanesthesia: from the time the anesthesia is turned off in the operatingroom; during transport to the recovery room; and through the entirerecovery phase until the patient is well awake.

Upper airway obstruction caused by a drug-induced depression of thecentral nervous system is preventable by applying positive pressurethrough the nasopharynx while leaving the oral cavity open to ambientpressure. The pressure differential thus created, splints the softtissues out of the airway with a natural pressure relief valve throughthe oral cavity. The maximum pressure obtainable is consistentlysufficient to relieve the obstruction, but is less than the 20centimeters of water that might send air to the stomach.

In accordance with one method of the present invention, nasal oxygen isapplied to an awake patient through a sealed nasal connection. Aconventional anesthesia administering apparatus, i.e., anesthesiacircuit, that is unable to provide air to a patient may be modified toinclude an air supply. In any event, a conventional anesthesiaadministering apparatus can be modified in accordance with the presentinvention to provide a sealed nasal connection. Nasal oxygen may beapplied as 100% oxygen, or a diluted form of oxygen by supplying air.

The sealed nasal connection may be provided by any device that may: beinserted into the nasal vestibule of the patient; provide a seal betweenthe device and an inner surface of the nasal vestibule; and administeran amount of a gas into the nasal vestibule via the nasal vestibularportion, wherein the seal promotes airway pressure buildup that issufficient to prevent obstruction of the airway during depression of atleast a portion of the nervous system and prevents escape of the gasfrom between the nasal vestibule and the device. For example, the sealednasal connection may be provided by a device having a nasal vestibularportion that is shaped as portions of the devices as disclosed in U.S.Pat. No. 5,533,506 to Wood, U.S. Pat. No. 4,702,832 to Tremble et al,U.S. Pat. No. 5,134,995 to Gruenke et al., U.S. patent application Ser.No. 09/430,038, the entire disclosures of which are incorporated hereinby reference.

Unlike the airflow delivery device 108 discussed above with reference toFIG. 1, the sealed nasal connection of the present invention cannotinclude ventilation holes. In particular, the ventilation holes 112 ofairflow delivery device 108 provide ventilation for CO₂ of the userduring expiration. However, such vent holes would be counter-productiveif included in the sealed nasal connection of the present invention. Inparticular, such vent holes would enable gas, that would otherwise havebeen forced into the airway of the patient to prevent airwayobstruction, to escape. Accordingly, the ability for the sealed nasalconnection of the present invention to prevent airway obstruction wouldbe reduced.

Once nasal oxygen is administered to the awake patient, the patient isforced to breathe in through the nose and out through the mouth. Thepatient will do so fairly comfortably as long as the nasal oxygen flowrate is adjusted to comfort.

Anesthesia is then induced, either intravenously or inhalationallythrough the sealed nasal connection. Then, when anesthesia is inducedand total relaxation of the pharyngeal muscles occurs, obstruction isprevented automatically as pressure within the anesthetic circuit buildsto prop open the patient's airway. With the mouth left open to ambientpressure in the deeply sedated patient, a pressure gradient isestablished which allows the soft palate and tongue to be propped out ofthe pharyngeal airway while at the same time creating a low pressureseal of the soft palate to the tongue which remarkably releases somewhatbetween 8 and 20 cm of water pressure. There is, in effect, a pressure“pop-off” valve that prevents a pressure build-up which would force airinto the stomach (20 cm of water is the reported threshold pressure).

Aspiration of gastric acid into the lungs may result in fatalpneumonitis, which is the classic nightmare of anesthesia practice.Over-inflation of the lungs with pharyngeal pressures in excess of 20 cmof water has been shown to blow air into the stomach. The resultantdistension of the stomach with air under pressure has been known tocause regurgitation and subsequent aspiration of acid into the lungs.However, C-PAP under 20 cm of water has been shown to oppose the refluxof acid up the esophagus by increasing the intra-thoracic pressure abovethe intra-abdominal pressure. This serves to create a pressure gradientwhich opposes reflux under anesthesia.

The reflex apnea triggered by obstruction is prevented and the patientresumes spontaneous respirations after a few seconds of central apnea,which may occur as a consequence to the direct depression of the centralnervous system by the anesthetic drug itself.

Deep levels of inhalational anesthesia can be achieved throughspontaneous and unassisted respirations. Then, with the sealed nasalconnection left in place, anesthesia and oxygenation can be sustainedduring, for example, a difficult intubation where ordinarily the removalof the oxygen mask would effectively remove adequate oxygenation fromthe patient. In theory, as long as 100% oxygen is provided at the levelof the open vocal chords, even a patient who is not breathing willremain well-oxygenated and viable for nearly an hour. In particular, thepatient will maintain adequate ventilation spontaneously when connectedto the closed anesthesia circuit with the nasal oxygen flow rateadjusted to maintain a positive pressure sufficient to preventobstruction. In other words, the patient is enabled to respireadequately, at surgical levels of anesthesia, totally free of aninvasive airway and manual or mechanized ventilation.

In accordance with a method of the present invention, a more strictmonitoring method is required to detect early partial airwayobstruction. For example, a more sensitive anesthetic circuit pressuregauge and a supra-sternal stethoscope may be used. In particular, aconventional pressure gauge in a conventional anesthesia circuit isscaled to approximately 160 units over the full circumference of itsface (1 unit=1 centimeter of water pressure). On the contrary, apressure gauge in accordance with the present invention would be moresensitive and have a scale of 40 units over the same circumference. Thefluctuations of the needle of the gauge would, therefore, be amplifiedby a factor of four making it a sensitive monitor of the alternatingpressures of the respiratory cycle. Further, as stated above, becausepressures in excess of 20 cm of water has been shown to blow air intothe stomach, the pressure gauge must be able to measure at least 20 cmof water. More importantly, the pressure gauge in accordance with thepresent invention should display the detected pressure at a precisionthat would readily communicate the difference between a inspiration andan expiration of the patient.

The airway pressure used under anesthesia, in accordance with thepresent invention, is not C-PAP as applied in the treatment ofobstructive sleep apnea. The airflow rate of a C-PAP generatorautomatically increases and decreases to maintain a constant positiveairway pressure. On the contrary, in accordance with the presentinvention, a gas flow rate to the patient is constant and is manuallyadjusted to a level that produces a positive pressure, which preventsobstruction. An apparatus in accordance with the present invention iscapable of providing a supplemental gas, such as for example oxygen orair, at a constant, adjustable, flow rate to the patient. Using a methodin accordance with the present invention, the supplemental gas issupplied in an amount such that there is a constant gas flow rate andthere is always a positive pressure, but the magnitude of the pressurevaries with respiration. This approach, i.e., using a constant gas flowrate, causes airway pressure to be higher on expiration than oninspiration. The varying pressure and constant gas flow rate provided bythe method and apparatus of the present invention is advantageous overconventional C-PAP because the constant gas flow rate and varyingpressure promotes a better venous return to the heart. The varyingpressure accompanied with the constant gas flow rate in accordance withthe present invention is termed alternating positive airway pressure.

The alternating positive airway pressure generated by the system inaccordance with the present invention has further beneficial effectskeeps the lungs expanded to a more optimal functional residual capacity,thereby increasing the oxygen reserves within the lungs, which in turnprevents atelectasis from collapse of the alveoli. Further, when air iscombined with oxygen, the alternating positive airway pressure generatedby the system in accordance with the present invention preventsatelectasis from oxygen absorption. Still further, the alternatingpositive airway pressure creates a positive intra-thoracic pressure,which serves to reverse any existing tendency towards reflux of gastriccontents up the esophagus, which might lead to aspiration into thelungs.

The system and method of use thereof in accordance with the presentinvention has still further beneficial effects. When inhalationalanesthesia is used, the carbon dioxide can be sampled from the scavengermask to monitor respirations and to assure that the scavenger is workingto remove exhaled gas. Depth of anesthesia is rapidly increased byincreasing flow rates to the nose so that no exhaled gas comes back intothe anesthesia circuit, but rather, is forced out through the mouth.Denitrogenation and oxygenation is facilitated along with the increasedflow rate of higher anesthetic gas concentrations into the lungs.Similarly, at the end of the procedure, anesthetic gasses are rapidlyeliminated by a unidirectional high flow of oxygen and/or air into theanesthetic circuit. In deep sedation (e.g. MAC, “MONITORED ANESTHESIACARE”), precise concentrations of oxygen can be monitored andadministered to the patient without escaping into the surgical fieldthereby reducing the fire hazard that accompanies the routine practiceof bringing oxygen into the proximity of cautery and laser devicesthrough a standard oxygen cannula.

Many conventional anesthetic delivery machines or facilities do not havethe capacity for adding controlled, pressurized air to the anestheticgasses. More importantly, no conventional anesthetic delivery machinesor facilities have the capacity for adding controlled, pressurized airor pure oxygen to the anesthetic gasses such that the total gas flowrate administered to the patient is sufficient to prevent obstruction ofthe airway during depression of the portion of the nervous system.

A device in accordance with the present invention includes a constantgas flow rate generator that is adaptable for use with a conventionalanesthetic delivery machine. The constant gas flow rate generator willadd a gas, such as oxygen or air, at a constant gas flow rate of a levelthat produces a positive pressure that is sufficient to prevent airwayobstruction. Furthermore, a constant gas flow rate generator inaccordance with the present invention may include an adjustment device,such as an automatic or manual adjustment device, for adjusting theconstant gas flow rate. An exemplary embodiment of an automaticadjustment device includes a gas flow rate meter that is operablyconnected to a gas flow valve. In particular, in operation of theexemplary embodiment of an automatic adjustment device, the gas flowrate may be set by the user. The gas flow rate may be subsequentlymonitored by the gas flow rate meter, the output of which controls thegas flow valve to open/close in the amounts required to maintain the gasflow rate set by the user. An exemplary embodiment of a manualadjustment device includes a gas flow rate meter that displays a gasflow rate to a user and a gas flow valve. In particular, in operation ofthe exemplary embodiment of a manual adjustment device, the gas flowrate as displayed by the gas flow rate meter is monitored by the user.The user will then operate the gas flow valve to open/close in theamounts required to maintain the gas flow rate desired by the user.

A gas delivery apparatus according to the present invention includes anasal insert having a gas passage therein for insertion into the nose,such as for example a device disclosed in U.S. application Ser. No.09/430,038, which is capable of forming a seal with the inner surface ofthe nasal vestibule. Bendable tubing is included in the apparatus. Thebendable tubing has a proximal portion connected to the nasal vestibularportion so as to be in gas communication with the gas passage of thenasal vestibular portion. The nasal vestibular portion flares outwardlywith respect to the gas passage therein.

The nasal vestibular portion may comprise a superior pole for engagingthe apex of a nasal vestibule. Further, an inferior pole of the nasalvestibular portion may be provided to engage an inferior nostril rim ofthe nasal vestibule. The superior pole may be elongated and rounded, andthe inferior pole may comprise an angled wedged shape. Thus, thesuperior pole, lodged in the apex of the nasal vestibule, may be shapedso as to help to direct the inferior pole against the inner surfaces ofthe nose to push the surfaces outward, thereby sealing.

The nasal vestibular portion may comprise a flexible material. In thiscase, a thin flap can be provided around the perimeter of the nasalvestibular portion for providing further sealing with the nasalinterior.

A second nasal vestibular portion may be provided to connect with thesecond nostril of a patient. The second nasal vestibular portion alsoflares outwardly with respect to the connection part. A head strapand/or an ear hook may be connected to the tubing to hold the tubing onthe head of the patient.

A nasal plug can also be adapted to close one nostril when only onenasal airway is supplied with gas. The nasal plug may be similar to thenasal airway which comprises a connection part and a nasal vestibularportion, but in this case would have its gas passage blocked, forexample by a cap. Alternatively, the cap could include a small openingto receive an oxygen tube to provide oxygen to the nostril.

In general, the present invention provides a gas administering methodfor administering gas to an airway of a patient having a nasalvestibule. The gas administering method is for use with a gasadministering apparatus comprising a gas source that is operable toprovide gas and a nasal vestibular portion arranged so as to receive thegas from the gas source. Further, the nasal vestibular portion iscapable of releasing the gas into the nasal vestibule. The methodcomprises inserting the nasal vestibular portion into the nasalvestibule, forming a seal between the nasal vestibular portion and aninner surface of the nasal vestibule, administering an amount of a gasfrom the gas source at a constant flow rate into the nasal vestibule viathe nasal vestibular portion, and administering an anesthetic to thepatient. The anesthetic induces depression of a portion of the nervoussystem of the patient. Furthermore, the seal causes airway pressurebuildup that is sufficient to prevent obstruction of the airway duringdepression of the portion of the nervous system and prevents escape ofthe gas from between the nasal vestibule and the nasal vestibularportion.

In one embodiment of the present invention, the gas administering methodfurther comprises administering oxygen into the nasal vestibule via thenasal vestibular portion, prior to the administering of the anesthetic.More particularly, the oxygen is provided from a source of gas that is100% oxygen. Alternatively, the oxygen is provided from a source of gasthat is a mixture of oxygen and nitrogen.

In another embodiment of the present invention, the administering of anamount of a gas comprises administering 100% oxygen.

In another embodiment of the present invention, the administering of anamount of a gas comprises administering air.

In another embodiment of the present invention, the gas administeringmethod further comprises detecting for an airway obstruction. Moreparticularly, the detecting for an airway obstruction comprises placinga stethoscope over the trachea at the supra-sternal notch.

In another embodiment of the present invention, the gas administeringmethod further comprises monitoring respiratory effort. Moreparticularly, the monitoring respiratory effort is performed via anelectrocardiogram monitor operating in a thoracic impedance mode.

In another embodiment of the present invention, the gas administeringmethod further comprises retrieving anesthetic that is expired from themouth of the patient. More particularly, the retrieving waist anestheticcomprises placing an anesthetic retrieving device over the face of thepatient.

In general, the present invention further provides a gas administeringmethod for administering a gas to an airway of a patient having a nasalvestibule. This method is for use with a gas administering apparatuscomprising a gas source that is operable to provide gas at a constantflow rate and a nasal vestibular portion having a shape such that thenasal vestibular portion provides an outward force on an inner surfaceof the nasal vestibule, due to elasticity of the nasal vestibule, forretaining the nasal vestibular portion in the nasal vestibule. Further,the nasal vestibular portion is arranged so as to receive the gas fromthe gas source. Still further, the nasal vestibular portion is capableof releasing the gas. The method comprises inserting the nasalvestibular portion into the nasal vestibule thereby forming a sealbetween the nasal vestibular portion and an inner surface of the nasalvestibule, administering an amount of a gas at a constant flow rate intothe nasal vestibule via the nasal vestibular portion, and administeringan anesthetic to the patient. The anesthetic induces depression of aportion of the nervous system of the patient. Finally, the seal causesairway pressure buildup that is sufficient to prevent obstruction of theairway while under sedation and prevents escape of the gas between thenasal vestibule and the nasal vestibular portion.

In general, the present invention still further provides a gasadministering method for administering gas to an airway of a patienthaving a nasal vestibule. This method is for use with an anestheticadministering apparatus comprising an anesthetic gas source that isoperable to provide an anesthetic. The method comprises fastening anasal vestibular portion to the anesthetic administering apparatus so asto receive the anesthetic gas from the anesthetic gas source (the nasalvestibular portion is capable of releasing the anesthetic gas into thenasal vestibule), inserting the nasal vestibular portion into the nasalvestibule, forming a seal between the nasal vestibular portion and aninner surface of the nasal vestibule, fastening a supplemental gassource to the anesthetic administering apparatus (the supplemental gassource is operable to provide a supplemental gas at a constant flow rateto the anesthetic administering apparatus) administering an amount ofthe supplemental gas from the supplemental gas source at a constant flowrate into the nasal vestibule, from the anesthetic administeringapparatus, via the nasal vestibular portion, and administering an amountof the anesthetic gas from the anesthetic gas source into the nasalvestibule, from the anesthetic administering apparatus, via the nasalvestibular portion. The anesthetic gas comprises an amount of anestheticsufficient to induce depression of at least a portion of the nervoussystem of the patient. Finally, the seal promotes airway pressurebuildup that is sufficient to prevent obstruction of the airway duringdepression of the at least a portion of the nervous system and preventsescape of the anesthetic gas or the primary gas from between the nasalvestibule and the nasal vestibular portion.

In general, the present invention still further provides a gasadministering system for administering gas to an airway of a patienthaving a nasal vestibule. The gas administering system comprises a gassource that is operable to provide gas at a constant flow rate and anasal vestibular portion arranged so as to receive the gas from the gassource. The nasal vestibular portion is capable of releasing the gasinto the nasal vestibule and is shaped to form a seal between the nasalvestibular portion and an inner surface of the nasal vestibule such thatthe gas released into the nasal vestibule causes airway pressure buildupsufficient to prevent obstruction of the airway during depression of atleast a portion of the nervous system. Further, the seal prevents escapeof the gas from between the nasal vestibule and the nasal vestibularportion.

In one embodiment of the present invention, the gas source comprises aprimary gas source for providing a primary gas and a supplemental gassource that is operable to provide a supplemental gas. Moreparticularly, the primary gas source may comprise an anesthetic gasproviding device. Further, the primary gas source may comprise an oxygenproviding device. Still further, the supplemental gas source maycomprise an air providing device having a flow rate adjustmentmechanism.

In another embodiment of the present invention, the gas administeringsystem further comprises a respiration monitor.

In another embodiment of the present invention, the gas administeringsystem further comprises a scavenging device for scavenging gas expiredfrom the mouth of the patient.

In another embodiment of the present invention, the gas administeringsystem further comprises a gas flow meter for measuring the gas flowrate of the gas provided by the gas source.

In another embodiment of the present invention, the natural curvature ofgas flow tubing is utilized to enhance performance of a nasal vestibulardevice.

In another embodiment of the present invention, a nasal vestibulardevice includes rounded portions that can be trimmed and that includeraised marks to provide a simple measuring system for incrementallytrimming the rounded portions to accurately fit increasingly smallernasal vestibules.

In another embodiment of the present invention, a nasal vestibulardevice includes an open portion to permit venting of expired CO₂ gasduring expiration wherein the open portion includes a raised line shapedto receive a plug cap, in the event that venting is not required.

In another embodiment of the present invention, a nasal vestibulardevice includes two nasal vestibular portions in communication with oneanother via an inter-connecting tube that may be cut to yield a nasalvestibular device having a single nasal vestibular portion to be used ina single nasal vestibule.

In another embodiment of the present invention, a connector may be usedto connect gas flow tubing together, wherein the connector includes aplurality of angled ridges on the inside perimeter thereof that areshaped to permit insertion of the tubing into the connector in a firstdirection and to inhibit the tubing from being pulled out of theconnector in a second direction.

In another embodiment of the present invention, a wireless electronicstethoscope transmitter is used with a breathing circuit stethoscope inaccordance with the present invention.

In another embodiment of the present invention, spirometers are usedwith a breathing circuit to measure the volume of the exhaled gas.

In another embodiment of the present invention, a home treatment systemincludes a nasal vestibular device, a heat and moisture exchanger forconserving heat and moisture, a vent, tubing and a C-PAP machine.

In another embodiment of the present invention, a transport andauxiliary power assembly permits convenient and continuous operation ofa C-PAP machine while being transported from the operating room to therecovery room.

Additional advantages of the present invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiments of the present invention. The invention itself,together with further objects and advantages, can be better understoodby reference to the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate embodiments of the present invention and,together with the description, serve to explain the principles of theinvention.

FIG. 1 illustrates a conventional system for treating sleep inducedapnea by providing a continuous positive airway pressure through thenose.

FIG. 2 generally illustrates a preferred embodiment of a gas deliveryapparatus according to the present invention.

FIG. 3A illustrates an exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention; FIG. 3B is a cross-sectional view of the nasalvestibular portion as depicted in FIG. 3A.

FIG. 4A illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention; FIG. 4B is a cross-sectional view of the nasalvestibular portion as depicted in FIG. 4A.

FIG. 5A and 5B illustrate how an embodiment of a nasal vestibularportion according to the present invention is inserted into the nasalvestibule of the patient.

FIG. 6 illustrates a gas delivery system in accordance with an exemplaryembodiment of the present invention.

FIG. 7 is a more detailed illustration of a gas delivery system inaccordance with the present invention.

FIG. 8 is a flow chart detailing an exemplary method of operation of gasdelivery system as illustrated in FIG. 7.

FIG. 9A is an exemplary subroutine for a step of increasing oxygen inthe flow chart as illustrated in FIG. 8; FIG. 9B is another exemplarysubroutine for a step of increasing oxygen in the flow chart asillustrated in FIG. 8.

FIG. 10A is an exemplary subroutine for a step of decreasing oxygen inthe flow chart as illustrated in FIG. 8; FIG. 10B is another exemplarysubroutine for a step of decreasing oxygen in the flow chart asillustrated in FIG. 8.

FIG. 11A is an exemplary subroutine for a step of administeringanesthetic in the flow chart as illustrated in FIG. 8; FIG. 11B isanother exemplary subroutine for a step of administering anesthetic inthe flow chart as illustrated in FIG. 8.

FIG. 12A is an exemplary subroutine for a step of increasing the amountof administered anesthetic in the flow chart as illustrated in FIG. 8;FIG. 12B is another exemplary subroutine for a step of increasing theamount of administered anesthetic in the flow chart as illustrated inFIG. 8.

FIG. 13A is an exemplary subroutine for a step of decreasing the amountof administered anesthetic in the flow chart as illustrated in FIG. 8;FIG. 13B is another exemplary subroutine for a step of decreasing theamount of administered anesthetic in the flow chart as illustrated inFIG. 8.

FIG. 14A illustrates another exemplary embodiment of a nasal vestibularportion that may be used with a gas delivery device in accordance withthe present invention; FIG. 14B is a view of the nasal vestibularportion as depicted in FIG. 14A as viewed directly into the gas deliveryopening; FIG. 14C is a view of the nasal vestibular portion as depictedin FIG. 14A as viewed opposite a direction from that of FIG. 14B.

FIG. 15A illustrates another exemplary embodiment of a nasal vestibularportion that may be used with a gas delivery device in accordance withthe present invention; FIG. 15B is a view of the nasal vestibularportion as depicted in FIG. 15A as viewed directly into the gas deliveryopening; FIG. 15C is a view of the nasal vestibular portion as depictedin FIG. 15A as viewed opposite a direction from that of FIG. 15B.

FIG. 16A illustrates another exemplary embodiment of a nasal vestibularportion that may be used with a gas delivery device in accordance withthe present invention; FIG. 16B is a view of the nasal vestibularportion as depicted in FIG. 16A as viewed directly into the gas deliveryopening; FIG. 16C is a view of the nasal vestibular portion as depictedin FIG. 16A as viewed opposite a direction from that of FIG. 16B; FIG.16D illustrates an unfolded protruding portion of the nasal vestibularportion of FIG. 16A.

FIGS. 17A–17D illustrate unfolded exemplary embodiments of protrudingportions of nasal vestibular portioris in accordance with the presentinvention.

FIG. 18A illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention; FIG. 18B is a cross-sectional view along line A—Aof the nasal vestibular portion of FIG. 18A; FIG. 18C is a view of thenasal vestibular portion of FIG. 18A without the sponge portion 1806.

FIG. 19 illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention.

FIG. 20 illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention.

FIG. 21 illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention.

FIG. 22 illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention.

FIG. 23 illustrates the application of the nasal vestibular portionillustrated in FIG. 22.

FIGS. 24A–24D illustrate exemplary embodiments of connector portions tobe used with nasal vestibular portions in accordance with the presentinvention.

FIG. 25A illustrates an exemplary embodiment of a connector portion of adevice that may be used with a gas delivery device in accordance withthe present invention; FIG. 25B illustrates the connector of FIG. 25Acombined with another exemplary embodiment of nasal vestibular portionsmay be used with the gas delivery device in accordance with the presentinvention; FIG. 25C is a left and right hand view of the combination ofthe connector portion and the nasal vestibular portions of FIG. 25B.

FIG. 26 illustrates the application of the combination of the connectorportion and the nasal vestibular portions of FIG. 25B.

FIG. 27 illustrates a gas delivery tube and a plug to be used inaccordance with the present invention.

FIG. 28 illustrates a gas delivery tube and a cap to be used inaccordance with the present invention.

FIG. 29 illustrates applications of a gas delivery tube and a nasalvestibular device in accordance with the present invention.

FIG. 30 illustrates another exemplary embodiment of a nasal vestibularportion that may be used with the gas delivery device in accordance withthe present invention.

FIG. 31 illustrates an in-line anesthesia-circuit stethoscope inaccordance with the present invention.

FIG. 32A illustrates an oblique view of an anesthesia or air circuitlaunching pad in accordance with the present invention; FIG. 32B is aside view of the launching pad of FIG. 32A; FIG. 32C is a side view of aportion of the launching pad of FIG. 32A.

FIG. 33 illustrates the application of the launching pad illustrated inFIGS. 32A–32C.

FIG. 34A is a side view of a constant-flow air generator in accordancewith one embodiment of the present invention; FIG. 34B is a front viewof a constant-flow air generator of FIG. 43A.

FIG. 35 is a side view of a constant-flow air generator and a draw-overvaporizer in accordance with one embodiment of the present invention.

FIG. 36 is an exemplary embodiment of acontinuous-pressure/constant-flow airflow generator in accordance withthe present invention.

FIG. 37 is another exemplary embodiment of acontinuous-pressure/continuous-flow airflow generator in accordance withthe present invention.

FIG. 38 is a detailed illustration of another embodiment of a gasdelivery system in accordance with the present invention.

FIG. 39 illustrates an exemplary embodiment of a gas delivery tube thatmay be used with a self-retaining nasal vestibular device, in accordancewith the present invention.

FIGS. 40A–40C illustrate further exemplary embodiments of a gas deliverytube that may be used with a self-retaining nasal vestibular device, inaccordance with the present invention.

FIGS. 41A–41C illustrate an exemplary embodiment of a nasal vestibulardevice, in accordance with the present invention.

FIG. 42 is a schematic diagram of the nasal vestibular device asillustrated in FIGS. 41A–41C.

FIG. 43 illustrates an exploded view of ridge 4112 of FIG. 41C.

FIG. 44 illustrates a plug cap for use with the nasal vestibular deviceillustrated in FIGS. 41A–41C.

FIG. 45 illustrates an embodiment of a connector used to connect gasdelivery tubing, in accordance with the present invention.

FIG. 46 illustrates an exemplary embodiment of a wireless electronicstethoscope transmitter, in accordance with the present invention.

FIGS. 47A and 47B illustrates exemplary embodiments of spirometers foruse with a breathing circuit, in accordance with the present invention.

FIG. 48 illustrates a system for use in the home treatment of a patientwith obstructive sleep apnea, in accordance with the present invention.

FIG. 49 illustrates a mesh filter for use with a heat moistureexchanger, in accordance with the present invention.

FIG. 50 illustrates a filter-plate for use with a heat moistureexchanger, in accordance with the present invention.

FIG. 51A–51C illustrate a transport and auxiliary power assembly, inaccordance with the present invention.

FIG. 52 illustrates an unfolded sheet a material to be used to form ahousing for the transport and auxiliary power assembly illustrated inFIGS. 51A–51C.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a more thoroughunderstanding of the present invention. It will be apparent, however, toone skilled in the art that the present invention may be practicedwithout the specific details.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a description of an exemplary method of and apparatusfor enabling a patient to adequately respire at surgical levels ofanesthesia without an invasive airway and manual or mechanizedventilation in accordance with the present invention.

During a pre-operative interview the patient is asked to confirm that hecan breathe in and out through his nose.

The patient is then taken into the operating room and assisted involuntarily positioning himself to comfort as appropriate through theanesthesia plan for facilitating the surgical intervention. Supine isthe usual starting position for positions requiring intubation of thetrachea. However, for superficial procedures in which the patient can beallowed to breath spontaneously, the patient can often be positionedawake and to comfort in the prone or lateral positions before inductionof anesthesia. The airway, more often than not, is more easilymaintained in these positions than in the supine position because of thelessened effects of gravity on the soft tissues (tongue and soft palate)that tend to collapse the airway. The awake patient will maintain apatent airway in any position, but the airway tends to collapse withdeep sedation and general anesthesia. An invasive airway device can betraumatic and, in the case of an endotracheal tube, may cause morephysiological disturbance than the surgery itself, if the anesthesia isnot profound. On the other hand, a major cause of morbidity andmortality in anesthesia is related to the steps taken to control thepatient's airway and to render it unreactive to the powerful stimulus ofan endotracheal tube. For example, it has been reported more than once,that the patient has been paralyzed to facilitate intubation only todiscover that the tube cannot be placed and the patient cannot bemanually ventilated. The prudent anesthetist takes care not to impedethe patient's own respiratory function without a well-considered reasonand without thorough preparation. By using the method and apparatus inaccordance with the present invention, the apparatus is inserted in theawake state, wherein a judgement can be usually made beforehand aboutthe adequacy of the patient's respirations under deep sedation.

After the patient is appropriately positioned, conventional monitors maybe attached to monitor the patient's vital signs, for example bloodpressure, pulse rate, temperature, respiration rate, etc. A nasal insertdevice in accordance with the present invention is then snugly fittedinto the nasal vestibule of the nose where the tissues are tougher andless sensitive than the mucosal lining of the turbinates and pharynx.Accordingly, an airtight seal is established fairly comfortably in theawake patient. This method of administering gas with the nasal insertdevice is less painful and traumatic to the patient than theconventional intubational method which uses an endotracheal tube.Further, a conventional nasal-pharyngeal airway is too long to becomfortably inserted into the deeper, more sensitive areas of the noseand nasopharynx.

The device of the present invention is then attached through standardconnections to a closed anesthesia circuit, i.e., the pressure reliefvalve of the circuit is closed, and the flow rate of 100% oxygen isadjusted to the patient's comfort.

As the monitors are attached and preparation is made for induction ofanesthesia, the awake patient is comfortably forced to breathe inthrough the nose and out through the mouth. The inhaled concentration ofoxygen approaches 100% and nitrogen exhaled through the lungs is moreeffectively washed out, i.e. the period of denitrogenation, by thecontinuous flow of oxygen out through the mouth. Accordingly, the lungsare rapidly filled with oxygen and reserves of oxygen within thefunctional residual cavity of the lungs approaches a factor of tenincrease, increasing dramatically the margin of safety as the criticalinduction period is approached. This is accomplished, by way of thepresent invention, in the comfortable, cooperative patient.

As preparation for induction of anesthesia approaches completion, thepulse oximeter usually approaches 100% oxygen saturation of thehemoglobin. The patient is then asked to take a breath through his nose.Nasal patency is confirmed by the deflation of a reservoir bag of theanesthesia circuit. At this point, the patient may be rapidly induced todeep sleep by a bolus of an induction drug, e.g. propofol. The airwaypressure of the anesthesia circuit is seen to rise from zero to apositive value as determined by adjustment of the oxygen in-flow of thecircuit. This pressure rise occurs as the soft tissues of the pharynxcollapse into the airway and as the pressure generated through the nosestints up the soft palate against the base of the tongue to create asealed pharyngeal passage pressurized somewhere between 5 and 20 cm ofwater pressure. This seal tends to release excess pressure before 20 cmof water pressure is achieved. As this is the threshold pressure in thepharynx beyond which gas is forced into the stomach, distension of thestomach with the attendant risk of reflux of gastric contents isnaturally avoided.

The patient may become apneic at first, but soon spontaneousrespirations resume. As the spontaneous respirations resume, thepressure gauge of a system in accordance with the present invention willrise and fall with inspiration and expiration.

At this point several options are available:

(A) If deep sedation-total intravenous anesthesia (TIVA) is to bemaintained, then the patient may be allowed to breathe spontaneouslywith a system in accordance with the present invention that is pressuredsufficiently by a constant gas flow rate so as to prevent airwayobstruction. Detection of partial airway obstruction is best detected byfixed-placement of a stethoscope over the trachea at the supra-sternalnotch. In addition, respiratory effort can be monitored by thoracicimpedance mode of the electrocardiogram monitor.

(B) If general inhalation anesthesia is planned, then a scavengingsystem may be established by placing the standard anesthesia face maskover the nasal insert and its connections and then connecting the maskby standard corrugating tubing to the scavenger port of the anesthesiamachine.

(C) If intubation is required, the nasal insert and its connection tothe anesthesia circuit can be left in place while the scavenging mask isremoved. This constant gas flow through the nose floods the pharynx withoxygen and the gas anesthetic to maintain oxygenation and anestheticdepth during even a prolonged intubation procedure. If at this point,the patient were to be paralyzed with a muscle relaxant and renderedtotally apneic, oxygenation would still be potentially satisfactory forperiods of time in excess of 20 minutes (without manual ventilation) bythe process of “mass movement” of 100% oxygen from the pharynx into thevacuum in the lungs created by absorption of oxygen from the lungs intothe blood. Thus, the method in accordance with the present inventionroutinely adds a large method of safety even for the unexpecteddifficult airway, which can be so disastrous to the patient.

FIG. 2 generally illustrates an exemplary embodiment of a gas deliveryapparatus according to the present invention. As illustrated in FIG. 2,the gas delivery apparatus 202 includes two branches of tubing 206 thatprovide gas to a gas delivery device 208. Gas delivery device 208includes two nasal vestibular portions 210 and 212 that are insertedinto the nasal vestibules 214 of the patient 204. A scavenging device216 may be used in conjunction with the gas delivery apparatus, and willbe described in greater detail below. The gas delivery apparatus 202further includes a gas input port 218 that receives gas from a gassource.

Gas delivery device 208 differs from airflow delivery device 108 of FIG.1 in that gas delivery device 208 does not have ventilation holes.

Vestibular portions 210 and 212 can be any shape that may: be insertedinto the nasal vestibule of the patient; provide a seal between the gasdelivery device 208 and an inner surface of the nasal vestibule; andadminister an amount of a gas into the nasal vestibule via the nasalvestibular portion, wherein the seal promotes airway pressure buildupthat is sufficient to prevent obstruction of the airway duringdepression of the portion of the nervous system and prevents escape ofthe gas from between the nasal vestibule and the gas delivery device208.

Many other exemplary embodiments of a nasal vestibular portions will nowbe discussed. A common general design feature of the exemplaryembodiments of the nasal vestibular portion is that each one may beinsertable into the nose of an awake patient with a minimum ofdiscomfort. In effect, each embodiment of the nasal vestibular portionmay be confined to the relatively insensitive and resilient tissues ofthe nasal vestibule. Another common general design feature of theexemplary embodiments of the nasal vestibular portion is that eachembodiment may seal with a nasal vestibule of the patient sufficient toachiever airway pressure of up to 20 centimeters of water with gas flowrates no greater than 20 liters/minute. Yet another design feature isthat each exemplary embodiment may be self-retaining within the nasalvestibule of the patient. That is to say, each may be capable offunctioning without straps or earhooks to hold it in place. In effect,the design may incorporate the following features: a) a superior poleinsertable into the relatively deep superior recess of the nasalvestibule (i.e., the ventro-medial recess contained within the nasaltip); b) an interior pole designed to hold the rim of the shallowinferior recess of the nasal vestibule (i.e., dorso-lateral recesscontained within the lateral flare of the base of the nose); c) rigidityin the longitudinal axis of the device which causes it to be fixed intothe nasal vestibule between the retaining wall of the superior recessand the retaining rim of the inferior recess; d) lateral walls of thedevice which may be solid or flare out from a central spine with lateralcompliance varying from zero to very compliant with the lateral andmedial surfaces of the nasal vestibule.

Because of the self-retaining qualities of the nasal vestibular portionsin accordance with the present invention, additional straps are notrequired to retain the gas delivery systems in the nose of the patient.Accordingly, as illustrated in the solid lines of FIG. 29, the gasdelivery tubes 2912 may be draped over the ears 2906 of the patient2902. Further, as illustrated in the dotted lines of FIG. 29, theself-retaining nasal vestibular portions 2908 additionally permit thegas delivery tubes 2912 to be draped over the head of the patient 2902.

Furthermore, the curvature of the gas delivery tubes may be exploitedwhen used in conjunction with the self-retaining nasal vestibularportions in accordance with the present invention. For example, thecurvature may be result of a “natural” curvature of the gas deliverytubes that is produced as a result of the coiling of the tubing duringthe manufacture. Further, the curvature may result from an explicitlydesigned self-sustaining curvature.

FIG. 39 and FIGS. 40A–40C illustrate exemplary embodiments of gasdelivery tubes that may be used with a self-retaining nasal vestibulardevice in accordance with the present invention. As illustrated in FIG.39, the gas delivery tube 3902 comprises a main portion 3904, an endportion 3906 and an end portion 3908. Each of end portion 3906 and endportion 3908 are illustrated as female connector portions. However, infurther exemplary embodiments, either one of end portions 3906 and 3908may be constructed as a male connecting end portion. End portion 3906 isadapted to connect to nasal vestibular device 3910 that includes a flowtube portion 3912 and nasal vestibular portion(s) 3914 to be insertedinto the nasal vestibule of the patient. End portion 3908 is adapted tobe connected to tubing of a breathing circuit. Further, as describedmore in detail below with respect to FIGS. 32 and 33, end portion 3908may be attached, via an attachment device 3920, to a launching pad 3916having a base 3918 and an attaching portion 3922.

The curvature of main portion 3904 is arranged in a manner illustratedin FIG. 39 in order to help hold the nasal vestibular device 3910 inplace. If the curvature of main portion 3904 results from the coiling ofthe tubing during the manufacturing thereof, then the arrangement asillustrated in FIG. 39 may be accomplished by slightly twisting endportion 3908 relative to end portion 3906, prior to connecting the endportion 3908 to the tubing of the breathing circuit and prior toconnecting end portion 3906 to nasal vestibular device 3910.Alternatively, if the curvature of main portion 3904 results from anexplicitly designed self-sustaining curvature, then no twisting of endportion 3908 would be required to achieve the arrangement illustrated inFIG. 39. With the concave surface 3924 of tubing 3904 oriented away fromthe patient, the tubing uses the chin of the patient as a fulcrum tolever the nasal vestibular device 3910 up and into the nasal vestibule.If the tubing is angled in an opposite direction, the nasal vestibulardevice 3910 tends to dislodge from the nasal vestibule.

FIGS. 40A–40C illustrate applications of three different curvatures ofgas delivery tube 3902.

With the convex surface of gas delivery tube 3902 being located, forexample, clockwise to about 45 degree position in connection with thenasal vestibular device, gas delivery tube 3902 can be looped around thechin to stabilize the nasal vestibular device without twisting the nasalvestibular device in the nose. This application is illustrated in FIG.40A.

As illustrated FIG. 40B, curvature of gas delivery tube 3902 is arrangedto be generally downward away from the head of the patient for use inhead and neck surgical procedures.

With the convex surface of gas delivery tube 3902 being rotated, forexample counter-clockwise to about 315 degree position in connectionwith the nasal vestibular device, gas delivery tube 3902 can be boughtup to the left side of the head without twisting the nasal vestibulardevice in the nasal vestibule. This application is illustrated in FIG.40C (and FIG. 29).

As discussed above, the curvature of the tubing, properly oriented,greatly facilitates the self-retaining characteristic of the nasalvestibular device. Accordingly, the nasal vestibular device will notrequire strap hooks, etc., to hold it in place. This self-retainingcharacteristic is, perhaps, the quality which most distinguishes thenasal vestibular device from conventional nasal inserts.

FIG. 45 illustrates an embodiment of a connector that may be used toconnect gas delivery tubing, in accordance with the present invention.As illustrated in FIG. 45, connector 4502 is operable to connect tubing4504, which is for example operably connected to a nasal vestibulardevice, with tubing 4506, which is for example operably connected to abreathing circuit. Connector 4502 includes a plurality of angled ridges4508 and a fixation tab 4510.

The inner diameter of connector 4502 corresponds with the outer diameterof connecting tubing 4504, so as to enable a female-to-male connectionbetween connector 4502 and tubing 4504. The outer diameter of connector4502 may correspond with the inner diameter of tubing 4506, so as toenable a male-to-female connection between connector 4502 and tubing4506. Angled ridges 4508 are shaped to permit insertion of tubing 4504in a direction toward tubing 4506 and so as to inhibit tubing 4504 frombeing pulled out of connector 4502 in a direction away from tubing 4506.

In an alternative embodiment, both the outer diameter of tubing 4506 andthe outer diameter of tubing 4504 may correspond with the inner diameterof connector 4502, so as to enable a female-to-male connection betweenconnector 4502 and tubing 4504 and to enable a female-to-male connectionbetween connector 4502 and tubing 4506. In such a case, angled ridges4508 are shaped to permit insertion of tubing 4504 in a direction towardtubing 4506, to permit insertion of tubing 4506 in direction towardtubing 4504, to inhibit tubing 4504 from being pulled out of connector4502 in a direction away from tubing 4506 and to inhibit tubing 4506from being pulled out of connector 4502 in a direction away from tubing4504.

Further, each outer end surface of connector 4502 may be tapered to fita standard connector, e.g., 15 mm.

Fixation tab 4510 aids in the withdrawal of connector 4502 frombreathing circuit connector tube 4506 and further provides a fixationpoint to the patient for stabilization of the apparatus.

Connector 4502 may be made of the same mold, and at the same time as theportion of the nasal vestibular device that is inserted into thepatients airway. Accordingly, total cost of the apparatus will bedecreased.

The benefits of the connector 4502 therefore are its ability to inhibitdisconnection from other tubing and its decreased manufacturing cost.However, a “softness” of the material of connector 4502 would require adesign different from conventional thin-walled hard connectors.Specifically, a conventional hard connector inserts into the tubing,i.e. a male-to-female connection. On the contrary, a “soft” connectorsuch as connector 4502 would require a thick wall to provide sufficientstructural integrity to allow insertion of the tubing for thefemale-to-male connection between connector 4502 and the tubing. Becauseconnector 4502 is designed to provide a female-to-male connectionbetween the connector and the tubing, thickness of connector 4502 doesnot affect gas flow through the connector. Accordingly, gas flow remainsconstant through the tubing and its connection with the breathingcircuit.

FIGS. 3A and 4A illustrate exemplary embodiments of nasal vestibularportions that may be used with the gas delivery device in accordancewith the present invention. FIGS. 3B and 4B are cross-sectionalillustrations of FIGS. 3A and 4A, respectively.

As illustrated in FIG. 3A, the nasal vestibular portion 30 includes agas flow tube portion 34, a gas delivery port 32 and a roundedprotruding portion 36 that is shaped so as to fit into a nasal vestibuleand form a seal with the inner surface of the nasal vestibule. Inparticular, the rounded protruding portion 36 prevents gas from escapingfrom the nasal vestibule to outside of the nasal vestibule.

FIG. 4A is a second exemplary embodiment of a nasal vestibular portion.A nasal vestibular portion 40 includes a gas flow portion 44, a gasdelivery port 42 and a bell-shaped protruding portion 46. Similar to theportion 36 of FIG. 3A, bell-shaped protruding portion 46 is shaped so asto form a seal with the inner surface of the nasal vestibule therebypreventing gas from escaping and the nasal vestibule.

FIGS. 5A and 5B illustrate insertion of a nasal vestibular portion intothe nasal vestibule. In the figures, a nasal vestibular portion 502 isinserted into the nose 500. In particular, a superior pole 504 isinserted into the nasal vestibule 506. A nasal vestibular airway 508 isthen rotated over the inferior nostril rim 510, and the sharp angle ofthe wedge 512 locks the nasal vestibular airway 508 in place in thenasal vestibule 506. Sealing forces of the nasal vestibular airway areagainst the inner surfaces of the nose to provide an outward force onthe inner surfaces of the nose.

As illustrated in FIG. 14A, the nasal vestibular portion 1400 includes agas flow tube portion 1404, a gas delivery port 1402 and a roundedoblong protruding portion 1406 that is shaped so as to fit into a nasalvestibule and form a seal with the inner surface of the nasal vestibule.In particular, the rounded oblong protruding portion 1406 includes arounded (wedge) shaped leading edge 1408 and a straight (gripping) edge1410 that maintains a self-retaining position within the nasal vestibuleof the patient. FIG. 14B is a view of the interior of the nasalvestibular portion 1400 whereas FIG. 14C is an exterior view of thenasal vestibular portion 1400.

As illustrated in FIG. 15A, the nasal vestibular portion 1500 includes agas flow tube portion 1504, a gas delivery port 1502 and a roundedmushroom shaped protruding portion 1506 that is shaped so as to fit intoa nasal vestibule and to form a seal with the inner surface of the nasalvestibule. In particular, the rounded mushroom shaped protruding portion1506 includes a rounded shaped leading 1508 and a straight (gripping)edge 1510. The rounded protruding mushroom shaped portion 1506 can behollow or solid. FIG. 15B is an interior view of the nasal vestibularportion 1500 of FIG. 15A. As illustrated in FIG. 15B, spine 1512provides rigidity in the longitudinal axis of the device which causes itto be fixed into the nasal vestibule between the retaining wall of thesuperior recess and the retaining room of the inferior recess. FIG. 15Cis an exterior view of the nasal vestibular portion 1500 of FIG. 15A.

As illustrated in FIG. 16A, the nasal vestibular portion 1600 includes agas flow tube portion 1604, a gas delivery port 1602 and a folded oblongprotruding portion 1612 that is, once folded, shaped so as to fit into anasal vestibule and form with a seal with the inner surface of the nasalvestibule. In particular, the folded oblong protruding portion 1612includes a rounded shaped leading edge 1608 and a straight (gripping)edge 1610. FIG. 16B is an interior view of the nasal vestibular portion1600. As illustrated in FIG. 16B, spline 1612 extends in thelongitudinal axis of the nasal vestibular portion to provide rigidity.FIG. 16C is an exterior view of the nasal vestibular portion 1600. FIG.16D is an interior view of an unfolded protruding portion 1612. Asillustrated in FIG. 16D, the unfolded portion 1612 is rounded. Asfurther indicated in FIG. 16D, the rounded unfolded portion may includeadditional longitudinal spines 1614 to provide further lateralcompliance. Please note that as opposed to a rounded shape, the unfoldedportion 1612 may have an oval shape.

FIGS. 17A–17D illustrate further exemplary embodiments of an unfoldedprotruding portion. In particular, FIGS. 17A–17D illustrate differentexemplary embodiments of splines that provide compliance which causesthe nasal vestibular portion to stay fixed into the nasal vestibulebetween the retaining wall of the superior recess and the retaining rimof the inferior recess. More specifically: FIG. 17A additionallyincludes lateral spines 1702; FIG. 17B includes circular spines 1703;FIG. 17C includes radially extending spines 1704; and FIG. 17D includesinterrupted spines 1705 that allow flexion at critical points 1706.

As illustrated in FIG. 30, the nasal vestibular portion gas flow tubeportion 3004 having a gas delivery port 1602 and a sampling tube 3006connection may be coupled with a protruding portion, for example asillustrated in any one of FIGS. 16D–17D. The sampling tube 3006 permitsthe gas being delivered to the patient to be sampled. The gas flow tubeportion 3004 may be adjustably coupled with a protruding portion suchthat the angle θ is set to maximize comfort to the patient and maintainstability.

As illustrated in FIG. 18A, the nasal vestibular portion 1800 includes agas flow tube 1804, a gas delivery port 1802, a resilient portion 1806and a spine portion 1804. The spine portion 1804 includes a leadingwedge shaped edge 1808 and a straight (gripping) edge 1810. FIG. 18B isa cross-sectional view of the nasal vestibular portion 1800 along linesA—A in FIG. 18A. As illustrated in FIG. 18B, spine 1802 is withinresilient portion 1806. Resilient portion 1806 may include a sponge-likematerial whereas spine 1802 includes a material that is more rigid thanthe resilient material 1806. FIG. 18C is an exterior view of nasalvestibular portion 1800 without resilient portion 1806. FIG. 18Cillustrates positioning of spine 1802 with respect to gas flow portion1804.

As illustrated in FIG. 19, a nasal vestibular portion 1900 includes agas flow tube portion 1904, a gas delivery port 1902 and a conicalprotruding portion 1906. Gas delivery port 1902 is beveled so as to havea superior pole 1908.

As illustrated in FIG. 20, a nasal vestibular portion 2000 includes agas flow tube portion 2004, a gas delivery port 2002 and an umbrellashaped portion 2006. The gas delivery port 2002 is beveled so as to havea superior pole 2008.

As illustrated in FIG. 21, a nasal vestibular portion 2100 includes agas flow tube portion 2104, a gas delivery port 2102 and a roundedumbrella shaped portion 2106. The rounded umbrella shaped portion 2106is in contact with the gas flow tube portion 2104 at a portion 2108,such that a portion of the gas flow tube extends above the roundedumbrella shaped portion 2106. Gas delivery port 2102 is beveled so as tohave a superior pole 2110.

As illustrated in FIG. 22, a nasal vestibular portion 2200 includes agas flow tube portion 2204, a gas delivery port 2202 and a protrudingportion 2210. The protruding portion 2210 includes a superior pole 2006,an inferior pole 2004 and a flat 2008. Spine 2212 provides rigidity tosuperior pole 2006.

FIG. 23 illustrates a nasal vestibule 2300 having nasal vestibularportion 2200 inserted therein. As illustrated in FIG. 23, superior pole2206 of the nasal vestibular portion 2200 is positioned within a recessof the nasal vestibule and engages edge 2302 of the nasal vestibule.Pliable inferior pole 2204 enables flap 2208 to lie adjacent to exteriorsurface 2304 of the nasal vestibule. The nasal vestibular portion 2200is well suited for infants or others with no well-defined infero-lateralridge of the nose. Specifically, inferior pole 2204 and flap 2208 areoperable to have an adhesive surface applied thereto to permit a sealagainst the exterior surface 2304 of the nose. The inferior pole 2204and flap 2208 adhere to the exterior surface-and may be held by manualpositioning or elastic strapping or, as indicated above, an adhesive.

Typically, a pair of nasal vestibular portions are used in accordancewith the present invention. FIGS. 24A–24D illustrate exemplaryembodiments of connector portions used to connect the nasal vestibularportions to a gas delivery system.

As illustrated in FIG. 24A, nasal vestibular portions 2404 having gasdelivery ports 2402 are connected to a gas flow tube 2406 via Yconnector 2408. FIG. 24B illustrates nasal vestibular portions 2404having gas delivery portions 2402, wherein the nasal vestibular portions2404 are connected to flow tube portion 2406 via a T connector 2410. Asillustrated in FIG. 24C, nasal vestibular portions 2404 having a gasdelivery port 2402, each have a gas flow portion 2606, respectively. Thetwo gas flow portions are connected via a connector, e.g. a string 2412.As illustrated in FIG. 24D, nasal vestibular portions 2404 having gasdelivery port 2402 each have a gas flow portion 2606, wherein the gasflow portions 2606 are connected via an interconnecting gas flow portion2414.

FIGS. 41A–41C illustrate an exemplary embodiment of a nasal vestibulardevice 4102 in accordance with the present invention. FIG. 41A is anoblique view, FIG. 41B is a side view and FIG. 41C is a bottom view ofnasal vestibular device 4102

Nasal vestibular device 4102 includes two nasal vestibular portions 4104each having a gas delivery port 4106. Further, nasal vestibular device4102 includes gas flow portion 4108 to provide gas to the gas deliveryports 4106. Further, nasal vestibular device 4102 includes a gasdelivery portion 4114 having a connecting portion operable to beconnected to a gas delivery system via gas delivery tubing. Nasalvestibular device 4102 still further includes an inter-connecting tube4110 for providing gas to both gas flow portions 4108, which will bedescribed in more detail below.

As further illustrated in FIGS. 41A–41C, each of nasal vestibularportions 4104 includes a central spine 4116 for providing sufficientrigidity to achieve a self retaining characteristic as discussed above.

As illustrated in FIG. 41C, each nasal vestibular portion 4104 has acurved end 4118 that includes raised marks 4120. Curved end 4118 may beeasily trimmed to fit different sized nasal vestibules. Raised marks4120 provide a simple measuring system for incrementally trimming curvedportions 4118 to accurately and reproducibly fit increasingly smallernasal vestibules. Further, as illustrated in FIG. 41C, curved endportions 4118 have a “toenail-like-configuration” such that they may beeasily trimmed with toenail clippers or scissors to retain a curvedshape for a comfortable fit in the nasal vestibule.

Raised line 4122, for example as illustrated in FIG. 41C, facilitatesthe cutting inter-connecting tube 4110 to yield a functionalsingle-insert device to be used in clinical situations where theopposite nasal vestibule of the patient is occupied by another device,e.g., a naso-gastric tube or fiber-optic scope.

Hole 4124 is provided to permit venting of expired CO₂ gas duringexpiration. Both raised line 4122 and ridge 4112 are shaped so as toreceive a plug cap, in the event that venting is not required. FIG. 43is an exploded view of ridge 4112.

FIG. 44 illustrates a plug cap for use with the nasal vestibular device4102. Plug cap 4402 includes a plug portion 4404 shaped to be insertedinto tubing 4110 at either portion of ridge 4112 or raised line 4122, inthe event that tubing 4110 has been cut at raised line 4122. Plug cap4408 further includes an annular locking portion 4406 shaped to lockover ridge 4112 or raised line 4122 to retain plug cap 4402 on tubing4110.

FIG. 42 is a schematic diagram of the nasal vestibular device 4102 ofFIGS. 41A–41C. As illustrated in FIG. 42, 4202 represents the nasalvestibular portions, 4204 represents the central spines, 4206 representsthe plug cap, 4208 represents the inter-connecting tube, and 4210represents a length of tube for connection to tubing of the breathingcircuit.

As illustrated in FIG. 25A, gas flow connector 2500 comprises connectorportion 2506, flow tube portion 2504, first vestibular portion deliverytube 2501, second vestibular portion delivery tube 2512, connecting tubeportion 2508 and gas delivery ports 2502. As illustrated in FIG. 25B, afirst vestibular portion 2514 and second vestibular portion 2506 arerespectively disposed on tube portions 2510 and 2512.

FIG. 26 illustrates a person having a gas flow connector and nasalvestibular portion of FIGS. 25A–25C inserted into nose 2506. Inparticular, the head strap 2612 placed over ears 2604 is connected tothe nasal vestibular device at 2610. The head strap is operable to pivotthe gas flow connector and nasal vestibular portion up into the nasalvestibule to lock behind the cartilaginous rim of the nasal vestibule.

FIG. 6 illustrates a gas delivery system in accordance with an exemplaryembodiment of the present invention. As depicted in FIG. 6, the gasdelivery system 600 includes a gas circuit 602 in addition to a nasalvestibular portion 604 for administering gas into the nasal vestibule ofthe patient, a positive pressure gauge 606 and a supplemental gasproviding system 608.

FIG. 7 is a more detailed illustration of a gas delivery system inaccordance with the present invention. As depicted in FIG. 7, gasdelivery system 600 includes a scavenging device 702, a gas analyzer704, a primary gas source 706, a scavenging vacuum 710, a CO₂ absorber712, a valve 714, a positive pressure gauge 716, a respirationmonitoring device 718, a supplemental gas source 720, a valve 722, avalve 724, a valve 726, gas delivery hose 728, and a nasal vestibularportion 730. Tubing 750 connects, in gas flow communication, scavengingdevice 702, gas analyzer 704, primary gas source 706, scavenging vacuum710, CO₂ absorber 712, valve 714, and valve 726. Tubing 752 connects, ingas flow communication, positive pressure gauge 716, respirationmonitoring device 718, supplemental gas source 720, valve 722, and valve724.

Item 754 is a connection point for tubing 752 to connect, in gas flowcommunication, with tubing 750. Similarly, item 756 is a connectionpoint for tubing 728 to connect, in gas flow communication, with tubing750. Accordingly, the tubing 752, and its associated devices, and tubing728 and its associated nasal vestibular portion may be attached to apre-existing gas delivery system comprising a scavenging device, a gasanalyzer, a primary gas source, scavenging vacuum, and CO₂ absorber.Alternatively, items 756 and 754 need not exist, wherein the entire gasdelivery system 600 is unitary.

A scavenging portion of gas delivery system 600 includes scavengingdevice 702 and scavenger vacuum 710. An exemplary embodiment ofscavenging-device 702 is a scavenging mask, which may be placed over theface of the patient. The scavenger vacuum 710 provides suction toretrieve gas expired through the mouth of the patient and therebyprevent leakage of an anesthetic gas, for example, into the surgicalfield. Furthermore, a portion of the scavenged gasses are analyzed bygas analyzer 704 in order to determine the composition of the gasses.Although a scavenging-portion is not required for the gas deliverysystem in accordance with the present invention, its addition may bedesired to prevent contamination of expired anesthetic into the surgicalfield and to reduce fire hazards resulting therefrom.

Gas source 706 provides the primary gas to be administered to thepatient. The primary gas is oxygen used to oxygenate a patient. Further,the primary gas may include an anesthetic medication to be administeredto the patient. Still further, the primary gas may include air,nitrogen, or another gas to be administered to the patient.Alternatively, the primary gas may be a mixture of oxygen, anestheticmedication, and another gas.

Valve 726 comprises a one-way valve which forces gas to flowunidirectional, thereby creating a circular flow of gas through CO₂absorber 712. CO₂ absorber 712, reduces the amount of CO₂ within the gascirculated through the gas delivery system 600.

Supplemental gas source 720 may be an air generator for providing aconstant flow rate of air. Valve 722 comprises an adjustable valve, forexample, a manually adjustable valve, for adjusting the gas flow rateprovided by supplemental gas source 720. Valve 724 is a unidirectionalvalve that prevents back flow of gas into supplemental gas source 720.

Supplemental gas source 720 may comprise a constant airflow generatorcapable of delivering accurate flow rates between 0 and 20 liters perminute within airway pressures of 0 to 20 centimeters of water. Such asupplemental gas source may provide fresh air to replenish oxygen and tofacilitate removal of CO₂. The air-generator may be used to deliver anaesthetic gas and to facilitate its removal at the end of anesthesia byincreasing flow rates to “flush-out” the system. A battery-operated,portable constant airflow generator may be used to maintain thefunctional residual capacity and to introduce air into the lungs of thehypoventilation patient to promote oxygenation and to preventatelectasis from absorption of oxygen during transport of the patientand recovery from anesthesia. Standard disposable anesthesia filters maybe incorporated into or used in conjunction with the constant airflowgenerator to allow the patient to breath the same ambient air as theanesthesia providers minus any possible bacterial and viralcontamination. The introduction of a cost-effective supply of air to theanesthesia circuit also decreases the risk of fire in the operatingroom. A manually-adjustable constant airflow generator (as opposed tothe constant pressure-variable flow generators used in the treatment ofsleep apnea) allows the pressure to vary within the anesthesia circuitto produce a more typical in-and-out movement of the reservoir bag,better monitoring of spontaneous respirations, better venus return andeasier detection of disconnects.

The constant airflow generator could take any of several forms, e.g.,piston airflow generator, diaphragm airflow generator, rotary vaneairflow generator, etc. FIGS. 34A and 34B illustrate a constant airflowgenerator in accordance with one embodiment of the present invention.Specifically, constant airflow generator 3400 comprises a housingsurrounding a brushless motor 3412, thereby eliminating sparks, andhaving sufficient power (and, a manual adjustable rate in one-half literincrements from 0 to 20 liters) to deliver a constant flow within apressure range of 0 to 20 cm of water. The motor includes rotary fan3402 and a power source 3408. This type of constant airflow generatorwill generate a constant pressure head of air to a regulator determinedby the tightness of fit between the rotary vanes and the constantairflow generator housing combined with the revolutions per minute andtorque of the motor. The power source may be a battery or an optionalinput from an external power source. Flows and pressures in excess ofthe capacity of the constant airflow generator would be dissipatedthrough the intake opening of the housing of the constant airflowgenerator. The constant airflow generator 3400 may include greaselessbearings thereby eliminating a use for oil to lubricate the system.Further, Teflon surfaces may be used to reduce friction of the rotaryparts. Air entering the system at input 3406 leaves the constant airflowgenerator at output 3404. A pressure-relief valve that “pops-off” at 20centimeters of water and a one way valve, which prevents tank oxygenfrom backing-up into the constant airflow generator may additionally beemployed at the output of the air-generator. By using a battery as thepower source 3408, the constant airflow generator is detachable from acharger and is readily transportable to another recharging location,e.g. a recovery room. An attachment device, such as a hook or strap, canbe provided to allow the constant airflow generator to be attached to astretcher rail during transport.

FIG. 35 illustrates a constant airflow generator 3400 placed in-linewith a “draw-over” vaporizer 3504. The combination of the constantairflow generator and the vaporizer adds anesthetic gas to a circlesystem or can totally power a simple non-rebreathing system requiring,at most, the addition of small amounts of tank oxygen (a simple“battle-field” system).

An anesthesia circuit can include a constant airflow generator inaccordance with the present invention, or in the alternative, a constantairflow generator in accordance with the present invention can be addedto a pre-existing anesthesia circuit. A standard “T-connector” could beused to connect the constant airflow generator to the circuit. It shouldbe noted that constant airflow generator is outside the circuit with thepurpose of adding air to the circuit. This as opposed to being placed inthe circuit for the purpose of speeding up circulation of anesthesiagases. If a pre-existing anesthesia circuit is modified to include aconstant airflow generator in accordance with the present invention, andthe constant airflow generator is subsequently removed, the input port2702 of the T connector can be plugged with a plug 2704 as illustratedin FIG. 27. Alternatively the input port 2802 of the T connector can becapped with a cap 2804 as illustrated in FIG. 28.

When detached from the anesthesia machine, the inflow T connector of thebreathing circuit can be capped with a cap having a port through whichoxygen can be delivered from a portable tank. The detached expiratorylimbed can be attached to a “T” to which is attached a reservoir bag anda conventional adjustable “pop-off” valve. The detached circuit with theattached constant airflow generator thereby becomes a self-sustainingpositive-pressure and fresh airflow breathing circuit with a capacityfor manual assistance.

A conventional bacterial filter can be incorporated to either or both ofthe intake and output of the constant airflow generator in accordancewith the present invention in order to sterilize the gas being deliveredto a patient.

Reservoir 718 is expandable and contractible in response to thedivergence of gas flowing therein, respectively. Reservoir 718 maytherefore be used as a visual indicator of the patient's respiration.

Positive pressure gauge 716, monitors the positive pressure of the gaswithin gas delivery system 600. Positive pressure gauge 716 should becapable of measuring pressure between 0 and 20 cm of water.Specifically, because pressures in excess of 20 cm of water has beenshown to blow air into the stomach, positive pressure gauge 716 must beable to measure at least 20 cm of water. More importantly, positivepressure gauge 716 in should display the detected pressure at aprecision that would readily communicate the difference between aninspiration and an expiration of the patient.

An exemplary method of operation of gas delivery system 600 asillustrated in FIG. 7 will now be explained with reference to the flowcharts of FIG. 8 through FIG. 13B.

Referring to FIG. 8, after nasal vestibular portion 730 has beeninserted into the nasal vestibule of the patient, the process is started(S802), and an alternating positive airway pressure is provided to thepatient (S804). In particular, supplemental gas source 720 provides asupplemental gas, the flow rate of which is constant and is manually setby manual adjustment valve 722. In this exemplary embodiment, thesupplemental gas is air. The gas enters the gas circuit 602 viaunidirectional valve 724 and eventually enters the nasopharynx 742 ofthe patient by way of nasal vestibular portion 730. The gas flow rate isset to achieve a positive pressure that is less than 20 cm of water,which is monitored through the positive pressure gauge 716. The gasflows from nasopharynx 742, past the epiglottis 744, into the trachea746 and continues into the lungs. Expiration of the patient providesback flow of expired gas back through nasopharynx 742 and through theoral cavity 736. Gas in oral cavity 746 is expired out through themouth, whereas back flow of gas in nasopharynx 742 returns into nasalvestibular portion 730 and returns into the gas delivery system 600.Respirations and expirations of the patient are monitored viaconstriction and expansion of reservoir 818. Further, as discussedabove, a scavenging system may be used wherein, for example, scavengingmask 702 is placed over the patient's face. Scavenging mask 802, asoperably connected to the scavenging vacuum 710, scavenges any gassesthat may be respired from the patient. Furthermore, gas analyzer 704analyses a portion of the scavenged gasses in order to determine thecomposition thereof.

Returning to FIG. 8, once the PPP is established, oxygen is administered(S806). In this exemplary embodiment, referring to FIG. 7, a second gassource, which is primary gas source 806 provides oxygen, which isultimately administered to the patient via nasal vestibular portion 730.However, primary gas source 806 may additionally be constructed so as toprovide oxygen via a mixture of oxygen and other gasses such as nitrogenor air. Furthermore, primary gas source 806 might not be needed ifsupplemental gas source 720 is operable to provide sufficient oxygen tothe patient.

Once the oxygen has been administered to the patient, the patient'soxygen levels are monitored (S808) by any conventional method, such aswith a pulse oximeter. If the oxygen level is determined to be too low(S818), then the oxygen provided to the patient is increased (S812). Onthe contrary, if the oxygen level of the patient is determined to be toohigh (S814), then the oxygen level is decreased (S816). Accordingly, aflow rate of gas from primary gas source 806 may be adjusted until thepatient is receiving an appropriate amount of oxygen.

If the oxygen supply must be increased, the constant flow rate of thesupplemental gas from the supplement gas source 720 should be adjustedaccordingly in order to maintain a constant total gas flow rate, whichis the sum of the supplemental gas flow rate and the oxygen flow rate.Ideally, if the oxygen flow rate is to be increased by a predeterminedamount, then the gas flow rate of the supplemental gas source 720 shouldbe concurrently decreased by an equal amount in order to maintain aconstant total gas flow rate of the combined oxygen and supplementalgas. A system may be easily constructed with conventional technology soas to easily accomplished this aspect. In particular, such a system mayinclude a servo system for automatically adjusting the flow rates of thesupplemental gas source 720 and the primary gas source 806 so as tomaintain a constant total gas flow rate.

Nevertheless, when it is determined that the oxygen level supplied tothe patient is too low (S810) wherein the oxygen supply must beincreased (S812), the two exemplary procedures as illustrated in FIGS.9A and 9B may be followed. In particular, FIGS. 9A and 9B illustrateexemplary procedures, wherein the increase in oxygen and the decrease inthe supplemental gas are not performed simultaneously. These procedurestherefore are not ideal because the total gas flow rate changes slightlywhen one gas flow rate is decreased but before the other gas flow rateis increased. However, the systems required to perform the proceduresdescribed with respect to FIGS. 9A and 9B may be less complicated andless expensive to construct because a servo system for automaticallyadjusting the flow rates would not be required.

As illustrated in FIG. 9A, at the start of the procedure (S902), the gasflow rate is determined (S904). In particular, the gas flow rate of thesupplemental gas provided by supplemental gas source 720 in addition tothe gas flow rate of primary gas source 706 is determined by way of agas flow sensor. Further, in one exemplary embodiment, the gas flow rateof the supplemental gas provided by supplemental gas source 720 isdetermined by a first gas flow sensor, whereas the gas flow rate ofprimary gas source 706 is determined by a second gas flow sensor. In anyevent, the oxygen flow rate is then increased by a predetermined amount(S906). Subsequently, in order to maintain a constant gas flow rate, thesupplemental gas is decreased in an equal amount (S908), and processstops (S910).

An alternate procedure is illustrated in FIG. 9B. At the start of theprocedure (S902), the gas flow rate is determined (S904). Then, thesupplemental gas is decreased by a predetermined amount (S912).Subsequently, in order to maintain a constant gas flow rate, the oxygenflow rate is increased in an equal amount (S914), and process stops(S916).

Returning to FIG. 8, wherein it is determined that the oxygenadministered to the patient needs to be decreased (S816), ideally, ifthe oxygen flow rate is decreased by a predetermined amount, then thegas flow rate of the supplemental gas source 720 should be concurrentlyincreased by an equal amount in order to maintain a constant total gasflow rate of the combined oxygen and supplemental gas. A system may beeasily constructed with conventional technology so as to easilyaccomplished this aspect. In particular, as discussed above, such asystem may include a servo system for automatically adjusting the flowrates of the supplemental gas source 720 and the primary gas source 806so as to maintain a constant total gas flow rate.

Nevertheless, when it is determined that the oxygen level supplied tothe patient is too high (S814) wherein the oxygen supply must beincreased (S816), the two exemplary procedures as illustrated in FIGS.10A and 10B may be followed. In particular, FIGS. 10A and 10B illustrateexemplary procedures, wherein the decrease in oxygen and the increase inthe supplemental gas are not performed simultaneously. These procedurestherefore are not ideal because the total gas flow rate changes slightlywhen one gas flow rate is decreased but before the other gas flow rateis increased. However, the systems required to perform the proceduresdescribed with respect to FIGS. 10A and 10B may be less complicated andless expensive to construct because a servo system for automaticallyadjusting the flow rates would not be required.

As illustrated in FIG. 10A, at the start of the procedure (S1002), thegas flow rate is determined (S1004). In particular, the gas flow rate ofthe supplemental gas provided by supplemental gas source 720 in additionto the gas flow rate of primary gas source 706 is determined by way of agas flow sensor. Further, in one exemplary embodiment, the gas flow rateof the supplemental gas provided by supplemental gas source 720 isdetermined by a first gas flow sensor, whereas the gas flow rate ofprimary gas source 706 is determined by a second gas flow sensor. In anyevent, the oxygen flow rate is then decreased by a predetermined amount(S1006). Subsequently, in order to maintain a constant gas flow rate,the supplemental gas is increased in an equal amount (S1008), andprocess stops (S1010).

An alternate procedure is illustrated in FIG. 10B. At the start of theprocedure (S1002), the gas flow rate is determined (S1004). Then, thesupplemental gas is increased by a predetermined amount (S1012).Subsequently, in order to maintain a constant gas flow rate, the oxygenflow rate is decreased in an equal amount (S1014), and process stops(S1016).

Returning to FIG. 8, once the oxygen level of the patient isappropriate, a general anesthetic may be administered (S818). In thisexemplary embodiment, the anesthetic is administered through inhalation.

Ideally, if the anesthetic is administered at a predetermined flow rate,then the gas flow rate of the gas from supplemental gas source 720 inaddition to the oxygen flow rate from the primary gas source 706 shouldbe decreased by an equal amount in order to maintain a constant gas flowrate of the combined anesthetic, oxygen and supplemental gas. A systemmay be easily constructed with conventional technology so as to easilyaccomplished this aspect. In particular, as discussed above, such asystem may include a servo system for automatically adjusting the flowrates of the supplemental gas source 720 and the primary gas source 806so as to maintain a constant total gas flow rate.

Nevertheless, when the anesthetic is to be administered to the patient(S818), the two exemplary procedures as illustrated in FIGS. 11A and 11Bmay be followed. In particular, FIGS. 11A and 11B illustrate exemplaryprocedures, wherein the anesthetic is administered in a predeterminedamount non-concurrently with a decreasing of the oxygen flow rate andthe supplemental gas flow rate by the predetermined amount. Theseprocedures therefore are not ideal because the total gas flow ratechanges slightly when one gas flow rate is decreased but before theother gas flow rate is increased. However, the systems required toperform the procedures described with respect to FIGS. 11A and 11B maybe less complicated and less expensive to construct because a servosystem for automatically adjusting the flow rates would not be required.

As illustrated in FIG. 11A, at the start of the procedure (S1102), thegas flow rate is determined (S104). In particular, the gas flow rate ofthe supplemental gas provided by supplemental gas source 720 in additionto the gas flow rate of primary gas source 706 is determined by way of agas flow sensor. Further, in one exemplary embodiment, the gas flow rateof the supplemental gas provided by supplemental gas source 720 isdetermined by a first gas flow sensor, whereas the gas flow rate ofprimary gas source 706 is determined by a second gas flow sensor. In anyevent, the flow rate of the oxygen and the supplemental gas is thendecreased by a predetermined amount (S1106). Specifically, the flow rateof the oxygen may be decreased by the predetermined amount, the flowrate of the supplemental gas may be decreased by the predeterminedamount, or some portion of each of the oxygen flow rate and supplementalgas flow rate may be decreased such that the total flow rate decrease isequal to the predetermined amount. Subsequently, in order to maintain aconstant gas flow rate, the anesthetic is administered in an equalamount (S1108), and process stops (S110).

An alternate procedure is illustrated in FIG. 11B. At the start of theprocedure (S1102), the gas flow rate is determined (S1104). Then, theanesthetic is administered by a predetermined amount (S1112).Subsequently, in order to maintain a constant gas flow rate, the flowrate of the oxygen and the supplemental gas is decreased by apredetermined amount (S1114), and process stops (S1116).

Returning to FIG. 8, once the anesthetic has been administered (S818),the patient is monitored so as to determine whether a sufficient amountof anesthetic is being administered (S820). If it is determined that theamount of anesthetic provided to the patient is too low (S822) then theamount of anesthetic provided to the patient is increased (S824).Alternatively, if it is determined that the amount of anestheticprovided to the patient is too high (S826), then the amount ofanesthetic provided to the patient is decreased (S828).

Ideally, if the anesthetic is to be increased by a predetermined flowrate, then the gas flow rate of the gas from supplemental gas source 720in addition to the oxygen flow rate from the primary gas source 706should be decreased by an equal amount in order to maintain a constantgas flow rate of the combined anesthetic, oxygen and supplemental gas. Asystem may be easily constructed with conventional technology so as toeasily accomplished this aspect. In particular, as discussed above, sucha system may include a servo system for automatically adjusting the flowrates of the supplemental gas source 720 and the primary gas source 806so as to maintain a constant total gas flow rate.

Nevertheless, when the anesthetic is to be increased (S824), the twoexemplary procedures as illustrated in FIGS. 12A and 12B may befollowed. In particular, FIGS. 12A and 12B illustrate exemplaryprocedures, wherein the anesthetic is increased in a predeterminedamount non-concurrently with a decreasing of the oxygen flow rate andthe supplemental gas flow rate by the predetermined amount. Theseprocedures therefore are not ideal because the total gas flow ratechanges slightly when one gas flow rate is decreased but before theother gas flow rate is increased. However, the systems required toperform the procedures described with respect to FIGS. 12A and 12B maybe less complicated and less expensive to construct because a servosystem for automatically adjusting the flow rates would not be required.

As illustrated in FIG. 12A, at the start of the procedure (S1202), thegas flow rate is determined (S1204). In particular, the gas flow rate ofthe supplemental gas provided by supplemental gas source 720 in additionto the gas flow rate of primary gas source 706 is determined by way of agas flow sensor. Further, in one exemplary embodiment, the gas flow rateof the supplemental gas provided by supplemental gas source 720 isdetermined by a first gas flow sensor, whereas the gas flow rate ofprimary gas source 706 is determined by a second gas flow sensor. In anyevent, the flow rate of the anesthetic is then increased by apredetermined amount (S1206). Subsequently, in order to maintain aconstant gas flow rate, the flow rate of the oxygen and the supplementalgas is decreased by the predetermined amount (S1208). Specifically, theflow rate of the oxygen may be decreased by the predetermined amount,the flow rate of the supplemental gas may be decreased by thepredetermined amount, or some portion of each of the oxygen flow rateand supplemental gas flow rate may be decreased such that the total flowrate decrease is equal to the predetermined amount. The process thenstops (S1210).

An alternate procedure is illustrated in FIG. 12B. At the start of theprocedure (S1202), the gas flow rate is determined (S1204). Then, theflow rate of the oxygen and the supplemental gas is decreased by apredetermined amount (S1212). Subsequently, in order to maintain aconstant gas flow rate, the anesthetic is increased by the predeterminedamount (S1214), and process stops (S1216).

Returning to FIG. 8, wherein it is determined that the anestheticadministered to the patient needs to be decreased (S828), ideally, ifthe anesthetic is to be decreased by a predetermined flow rate, then thegas flow rate of the gas from supplemental gas source 720 in addition tothe oxygen flow rate from the primary gas source 706 should be increasedby an equal amount in order to maintain a constant gas flow rate of thecombined anesthetic, oxygen and supplemental gas. A system may be easilyconstructed with conventional technology so as to easily accomplishedthis aspect. In particular, as discussed above, such a system mayinclude a servo system for automatically adjusting the flow rates of thesupplemental gas source 720 and the primary gas source 806 so as tomaintain a constant total gas flow rate.

Nevertheless, when the anesthetic is to be decreased (S828), the twoexemplary procedures as illustrated in FIGS. 13A and 13B may befollowed. In particular, FIGS. 13A and 13B illustrate exemplaryprocedures, wherein the anesthetic is decreased in a predeterminedamount non-concurrently with an increasing of the oxygen flow rate andthe supplemental gas flow rate by the predetermined amount. Theseprocedures therefore are not ideal because the total gas flow ratechanges slightly when one gas flow rate is decreased but before theother gas flow rate is increased. However, the systems required toperform the procedures described with respect to FIGS. 13A and 13B maybe less complicated and less expensive to construct because a servosystem for automatically adjusting the flow rates would not be required.

As illustrated in FIG. 13A, at the start of the procedure (S1302), thegas flow rate is determined (S1304). In particular, the gas flow rate ofthe supplemental gas provided by supplemental gas source 720 in additionto the gas flow rate of primary gas source 706 is determined by way of agas flow sensor. Further, in one exemplary embodiment, the gas flow rateof the supplemental gas provided by supplemental gas source 720 isdetermined by a first gas flow sensor, whereas the gas flow rate ofprimary gas source 706 is determined by a second gas flow sensor. In anyevent, the flow rate of the oxygen and the supplemental gas is thenincreased by a predetermined amount (S1306). Specifically, the flow rateof the oxygen may be increased by the predetermined amount, the flowrate of the supplemental gas may be increased by the predeterminedamount, or some portion of each of the oxygen flow rate and supplementalgas flow rate may be increased such that the total flow rate increase isequal to the predetermined amount. Subsequently, in order to maintain aconstant gas flow rate, the flow rate of the anesthetic is decreased bythe predetermined amount (S1308). The process then stops (S1310).

An alternate procedure is illustrated in FIG. 13B. At the start of theprocedure (S1202), the gas flow rate is determined (S1304). Then, theanesthetic is decreased by a predetermined amount (S1312). Subsequently,in order to maintain a constant gas flow rate, the flow rate of theoxygen and the supplemental gas is increased by the predetermined amount(S1314), and process stops (S1316).

Steps S818 through S830 are repeated until the proper amount ofanesthetic is provided to the patient, wherein the process stops (S830).

If the anesthetic is to be administered intravenously, then a simplifiedembodiment of the present invention may be used. In particular, theoxygen provided to the patient is adjusted to a proper level while thesupplemental gas provider administers supplemental gas to maintain aconstant gas flow rate. In other words, the oxygen and supplemental gasmay not be further adjusted so as to accommodate an additional gas flowof anesthetic, because the anesthetic has been administeredintravenously.

In the exemplary embodiment described above, supplemental gas source 706provides both oxygen and anesthetic. In an alternative embodiment, twoseparate gas sources may be provided, one for administering oxygen andone for administering anesthetic. In another embodiment, supplementalgas source only administers oxygen, wherein an inhalation anesthetic isnot required.

Further, the device according to the present invention can be toleratedwithout anesthesia or sedation. It is less likely to causeclaustrophobia. Further, while existing devices are cumbersome andsurround the face and head with a mask and straps, and a bag, the nasalvestibular airway can be paired and worn like eyeglasses with hooks orstraps over the ears.

Furthermore, the nasal vestibular airway according to the presentinvention may be applied to deeply sedated patients in dental surgery.The device of the present application may even be considered for use inveterinary medicine, where there is no satisfactory means of assisting aspontaneously breathing but respiratory-compromised animal.

FIG. 38 is a more detailed illustration of a gas delivery system inaccordance with another embodiment of the present invention. The gasdelivery system of FIG. 38 is similar to that as illustrated in FIG. 7.However, the gas delivery system 3800 as depicted in FIG. 38 differsfrom gas delivery system 600 as depicted in FIG. 7 in that the gasdelivery system 3800 includes a breathing-circuit stethoscope 3802.Accordingly, a discussion of the similar aspects between the gasdelivery system 3800 as depicted in FIG. 38 and the gas delivery system600 as depicted in FIG. 7 will not be repeated.

A breathing-circuit stethoscope or in-line anesthesia circuitstethoscope allows quick and convenient monitoring of amplified breathsounds within the anesthesia circuit. This is particularly useful in thespontaneously breathing, non-intubated patient where the flow of airthrough the tubing and the valves of the circuit combine with flowthrough the patient's anatomy to produce sounds characteristics ofadequate flow, obstructed flow, circuit disconnects, fluid in theairway, etc. These sounds are generally much amplified by the circuitover those that might be heard by direct application of a stethoscope tothe patient. The circuit stethoscope may be permanently attached to theanesthesia machine without need to adapt to each patient individually.When connected by microphone or a wireless transmitter (such as, forexample, in combination with input from other sources, e.g., pre-cordialstethoscope, monitor speaker, etc.) it becomes an“anaesthetist-friendly” continuous multi-parameter monitor.

FIG. 31 illustrates an exemplary embodiment of an breathing circuitstethoscope in accordance with the present invention. As illustrated inFIG. 31, the breathing circuit stethoscope includes a T-connector 3102having an input port 3104 and an output port 3106 for connection withgas flow tubes of the anesthesia circuit, a port 3108 for communicationwith a diaphragm 3110 and a bell cap portion 3102. The diaphragm maycomprise, for example, a thin plastic providing an air-tight pressureseal over port 3108. The bell cap 3102 may comprise a plurality ofconnector ports, for example 3114 and 3116. As illustrated in FIG. 31,connector port 3114 is operable to be connected to a stethoscope 3118such that a doctor may monitor the sounds in the anesthesia circuit.

Furthermore, connector port 3116 is operable to be connected withmicrophone 3120 which may additionally be attached to a wirelesselectronic stethoscope transmitter 3122 of which may additionally beconnected to a pre-cordial stethoscope 3124 to monitor the heart and amonitor speaker 3126.

FIG. 46 illustrates an exemplary embodiment of a wireless electronicstethoscope transmitter 3122 that may be used with the breathing circuitstethoscope in accordance with the present invention. As illustrated inFIG. 46, wireless electronic stethoscope transmitter 3122 includes atransmitter 4604, a speaker 4606, a transmitter on/off switch 4608, aspeaker volume/on/offswitch 4610, a power source 4612, an attachmentdevice 4614, a signal input 4620 and signal output 4618. Transmitter4604 may comprise any type of signal transmitter, for example aninfrared transmitter, that is operable to transmit a signal to othermonitoring equipment. Speaker 4606 provides an audio sound, i.e.,breathing sounds of the patient, corresponding to the signal input bysignal input 4620. Power source 4612 may include any type of portablepower source, such as for example a battery or a capacitor, and may berechargeable. Attachment device 4614, for example a hook, is operable tosuspend portable breath sound monitor 4602, for example from an I.V.pole or bed rail. Attachment device 4614 may additionally include aswivel 4616 operable to permit the portable breath sound monitor to turnas needed while hanging from an IV pole or bed rail.

The speaker 4606 combined with the transmitter 4604 in portable breathsound monitor unit 4602 enables both units to be used at the same timeor be separately turned off. An amplifier in wireless electronicstethoscope transmitter 3122 receives an input signal from input 4620 toamplify the breathing sounds of a patient to be broadcast throughspeaker 4606 and/or transmitter 4604. Wire 4622 connected to microphone4624 enables the breathing sounds to be received from the circuitstethoscope 4628. Further, a stethoscope attachment 4626 mayadditionally be connected to the circuit stethoscope 4628. Wirelesselectronic stethoscope transmitter 3122 may be placed, for example on atable top or suspended by attachment device 4614 from a rail of I.V.pole. As discussed above, the hook swivels to allow the best orientationof the suspended unit.

Because the wireless electronic stethoscope transmitter 3122 includes anattachment device and a power source, the transmitter is moveablethroughout the surgical theater. Furthermore, the wireless electronicstethoscope transmitter 3122 maybe attached to the patient's bed so thatit may be transported with the patient as the patient is transported todifferent rooms throughout the entire recovery phase until the patientis well awake.

Transmitter 4604 may additionally transmit a signal corresponding to theinput signal from input 4620 to headphones of a specific person. In thismanner, speaker 4606 may be turned off so that the detected signalprovided by input 4620 will not be outputted from speaker 4608 to avoiddistracting others in the area.

Because of the nature of the use of the wireless electronic stethoscopetransmitter 3122, transmitter 4604 need only be required to process asingle channel of sound data. More particularly, stereophonic processingis not required, therefore the circuitry needed for the wirelesselectronic stethoscope transmitter 3122 is relatively uncomplicated andinexpensive to manufacture.

The shape of wireless electronic stethoscope transmitter 3122 in FIG. 46is merely illustrative, and the shape may take any form in order toachieve the desired purposes discussed above. In an exemplaryembodiment, a wireless electronic stethoscope transmitter may take theform of a ball comprising an outer shell made of impact resistantmaterial, such as impact resistant rubber or impact resistant plastic.Such a ball shaped wireless electronic stethoscope transmitter 3122maybe “tossed” or placed in the bed of a patient. Further, a foldable orcollapsible handle may be incorporated into the ball shaped wirelesselectronic stethoscope such that once unfolded or extracted, the handlemay be used to hang the ball shaped wireless electronic stethoscope onan I.V. pole or rail of a bed.

A launching pad may provide a fixing point for the relatively heavy andcumbersome gas circuit tubing. This fixing point allows greater mobilityand less chance of dislodgement of the relatively light and flexibletubing which is the interface between the airway device and the circuit.The launching pad can be attached, for example, to the patient's chestsuch that it is repositionable to facilitate optimum placement.

FIG. 33 illustrates the use of a launching pad 3200. In particular, asillustrated in FIG. 33, launching pad 3200 fixes anesthesia circuittubing 3304 to a patient 3302 such that the gas delivery tube 3308 caneasily reach the patient. Pivotable connector 3306 provides a connectingportion between tubing 3308 and 3304.

FIGS. 32A–32C illustrate a launching pad in accordance with oneembodiment of the present invention. Specifically, launching pad 3200comprises a rigid pad 3202 having attachment portions 3204 and a hinge3206. Attachment portions 3204 may comprise loops that permit tying downof the hoses of the anesthesia breathing circuit. Any other detachmentdevices, e.g., velcro, may be used. Hinge 3206 may comprise a flexionhinge to allow the pad to better conform to the patient's chest.Non-conductive adhesive gel 3208 adheres the launching pad to thepatient. Separating layer 3212 separates adhesive gel 3208 from adhesivelayer 3210. The separating layer may comprise material such as paper,plastic or any material capable of separating the two adhesive layers.As illustrated in FIG. 32C, removable backing 3214 can be pealed back soas to adhere adhesive layer 3210 to pad 3202. Accordingly, the adhesivenon-conductive gel pads may be removed such that the rigid pad 3202 maybe reusable.

Flow regulators may additionally be added throughout an anesthesiacircuit in accordance with the present invention. FIGS. 36 and 37provide exemplary embodiments of flow regulators in accordance with thepresent invention.

The first embodiment of a flow regulator as discussed above and asillustrated in FIG. 36, includes an input port 3602 that receives gasfrom the anesthesia and output port 3606 provides the gas back to theanesthesia breathing circuit after passing unit directional valve 3608that prevents back flow of the gas into the flow regulator. A flowbobbin 3614 in a graduated conical cylinder is operable to movelaterally in accordance with the amount of fluid flowing through theflow regulator. An adjusting knob 3602 is operable to control the amountof fluid flowing through the flow regulator by adjusting valve 3610thereby permitting an amount of air to bypass through bypass 3604.Airflow leaving the constant airflow generator would fast pass through a“flush valve” which would allow two options: In the “normal” positionairflow would be directed to the regulator. In the “flush” position,airflow would bypass the regulator and enter the breathing circuit atthe full-flow capacity of the constant airflow generator. The purposewould be to fill the reservoir bag and the breathing circuit to capacityas fast as possible. The “flush” could be a push valve similar to thatused an most anesthesia machines.

The regulator would be a variable-orifice resistor to airflow which, ata fixed pressure within the capacity of the constant airflow generator,would allow a fixed rate of airflow. There are several types of variableorifice regulators which might be used, but one similar to a standardconical-shaped screw-pin used on anesthesia machines would work well.

FIG. 37 is another embodiment of a fluid flow regulator. In particular,input port 3702 receives gas from the anesthesia circuit whereas outputport 3706 returns the gas to the anesthesia circuit after passing unitdirectional valve 3708 that prevents back flow of the gas into the flowregulator.

A conventional spirometer may be used in conjunction with conventionalbreathing circuits. However, conventional spirometers have a problemmeasuring the amount of air leaving the lungs when used in conventionalbreathing circuits. When the breathing circuit is pressurized (e.g.,with C-PAP), the flow characteristics within the breathing circuit areoften altered in such a way as to make the conventional spirometersuseless. For example, when mounted in the expiratory limb of thebreathing circuit, a conventional electronic spirometer can be defeatedby the continuous leakage flow that is typical of C-PAP applications. Inparticular, the flow indicator of the electronic spirometer typicallygoes off scale and does not indicate the rhythmic fluctuations ofrespiratory ebb and flow. On the other hand, a conventional mechanicalspirometer such as a “Wright” spirometer works very well as the speed ofthe rotary needle gage fluctuates nicely to indicate precise volumes oninspiration and pauses on expiration. However, conventional mechanicalspirometers are precision instruments, the expense of which might behard to justify for the occasional user of an anesthesia C-PAP system.

A spirometer in accordance with the present invention may be used with abreathing circuit to measure the volume of exhaled gas. FIGS. 47A and47B illustrate two exemplary embodiments of spirometers for use with abreathing circuit in accordance with the present invention. Asillustrated in FIGS. 47A and 47B, the spirometers, 4702 and 4724,respectively, are adapted to be placed in-line of a breathing circuit soas to communicate between the CO₂ scrubber 4718 and the patientbreathing circuit connector 4722.

In first embodiment as depicted in FIG. 47A, the spirometer 4702includes a light-weight float 4704 in a large, (e.g., 22 mm) taperedtube 4706 is operable to connect in-line with a breathing circuit. Thefloat 4704 and tapered tube 4706 create a variable flow orifice typicalof a flow meter. Spirometer 4702 is distinguished from conventionalspirometers in that spirometer 4702 includes an input 4712 and an output4714 designed to permit in-line connection with the breathing circuit.Further, the relatively large float 4704 and tapered tube 4706 permitflows in a low-pressure (e.g., 0–20 cm of water) C-PAP system to beaccurately indicated with very low resistance to flow. A flow restrictorpin 4708 across tapered tube 4706 prevents float 4704 from occluding thetube.

Flow meters similar to that of spirometer 4702 have been employed inanesthesia machines, but are used in high-pressure (e.g., 55 mm ofmercury) gas supply lines to the circuit, not in a setting in accordancewith the present invention (0–22 cm of water). Further, a conventionaldevice called an incentive spirometer is somewhat similar inconstruction to spirometer 4702, however the incentive spirometer is notdesigned to fit in-line with a breathing circuit.

In another embodiment as depicted in FIG. 47B, the spirometer 4724includes, an in-line turbine 4732 and a housing 4730. Spirometer 4724 isincluded within the inspiratory limb of the breathing circuit such thatinput 4726 of spirometer 4724 is in communication with the output 4716of CO₂ scrubber 4718 and such that output 4728 of spirometer 4724 is incommunication with an input 4720 of patient breathing circuit connector4722. In-line turbine 4732 has colored rotatable blades, or veins, thatare clearly visible through a clear portion 4734 of housing 4730. Thecolored blades are operable to spin with a variable velocity indicativeof the ebb and flow of inspiration superimposed upon a constant flow ofgas through the breathing circuit. A side of the housing 4730 that isopposite the clear portion is colored a different color than that of theblades (or the opposite side may be opaque). Accordingly, as the flow ofgas through the breathing circuit increases in volume, the rotationalspeed of the color blades increases thereby changing the perceived colorof the spirometer 4724. Therefore, a viewer viewing the spinning coloredblades, would recognize a change in intensity of the spinning blades asa result of the perceived changing color. This perceived change in colordirectly corresponds to the ebb and flow of the gas passing throughin-line turbine 4732. Therefore, the perceived change in color informsthe viewer of the breathing of the patient.

FIG. 48 illustrates a system for use in the home treatment of a patientwith obstructive sleep apnea, in accordance with the present invention.The system of the present invention is more beneficial than conventionaldevices for obstructive sleep apnea because the system of the presentinvention is less cumbersome, includes a built-in humidifying system forinspired air, suppresses noise and further includes a re-usable and usermaintained heat and moisture exchanger.

The home treatment system 4802 includes a nasal vestibular device 4804,tubing 4806 a heat and moisture exchanger 4808 for conserving heat andmoisture, a vent 4810, tubing 4816 and a C-PAP machine 4818. System 4802may additionally include optional vent tubing 4812 and hollowed andvented ball 4814.

Tubing 4806 is much smaller than tubing used in conventional devices forobstructive sleep apnea. Specifically, conventional tubing forconventional devices, which are approximately 22 mm, have a lowerresistance to air flow. On the contrary, tubing 4806, preferably in therange of 17–15 mm permits comfortable spontaneous respirations and ismuch less cumbersome. Moreover, any resistance to flow is negated byadjustment of the airflow generator, e.g., the C-PAP machine, poweringthe system.

Conventional devices for home treatment of obstructive sleep apneainclude a vent that is as close to the nose of the user as possible inorder to reduce the “dead space” that allows re-breathing of CO₂. On thecontrary, in accordance with the present invention, vent 4810 includes avent hole 4820 that is separated from the nose of the patient via atleast the distance of tubing 4806 and the heat moisture exchanger 4808.The small added increase in dead space is comfortably and automaticallycompensated for in the spontaneous breathing patient. Further, optionalvent tubing 4812 may be added to vent 4810 to direct the “hissing” soundof escaping air out of earshot of the user and others. Tubing 4812 mayterminate at a large vented sphere 4814 in order to prevent air flowfrom becoming obstructed.

Heat and moisture exchanger 4808 may be configured in several ways. Forexample, it may comprise metal or plastic parts and be designed to bedisassembled by the user. Further, it may include disposablewater-trapping filters. Such filters may be of a reusable plastic ormetal mesh or filter-plate which can be cleaned and sterilized by theuser, for example by soaking in alcohol and rinsing thoroughly in water.FIGS. 49 and 50 illustrate examples of a mesh filter 4902 andfilter-plate 5002, respectively.

There are several C-PAP machines marketed for home, hospital and campinguse which employ 12 volt direct current systems with an optional batteryadapter. A transport and auxiliary power assembly in accordance with thepresent invention, allows such C-PAP units to be used withoutmodification in an attachment to a light-weight battery and handleassembly which allows the machine to be operated conveniently andcontinuously from the horizontal position to the vertical position whilebeing transported from the operating room to the recovery room. FIGS.51A–51C and 52 illustrate a transport and auxiliary power assembly for aC-PAP machine in accordance with the present invention.

As illustrated in FIG. 51A, a carrying member 5102 is shaped as afour-sided platform to support a C-PAP machine 5104 and a battery pack5106, mounted adjacent to C-PAP machine 5104 in a horizontal or“tabletop” position. During transport, as illustrated in FIG. 51B, theassembly is capable of being suspended vertically by a handle-rail-hookportion 5108 from a rail 5110 of a patient's bed. FIG. 51C illustrates aside view of carrying member 5102 when carried in the vertical positionfrom a rail of a patient's bed. As illustrated in FIG. 51C, output 5112of C-PAP machine 5104 is accessible for use during transport.

Battery pack 5106 and the C-PAP machine may be held together and tomember 5102 by detachable fixation systems, such as small “velcro”fixation tabs, from which the components can easily be separated.Further, C-PAP machine 5104 and battery pack 5106 may be secured tocarrying member 5102 via a strap enclosing the components.

Returning to FIG. 51A, battery pack 5106 may include a chargingreceptacle 5114 for charging the battery pack, a charging light 5116 forindicating when the battery pack is being charged and a warning light5118 for indicating when the battery level is below a predeterminedthreshold.

FIG. 52 illustrates a single sheet 5200 of material that may be used toform carrying member 5102. Sections 5202, 5204, 5206, 5208, 5210 and5212 are separated by a plurality folding lines 5214. Sections 5202,5204 and 5206, once folded, form hand-rail-hook portion 5108. Portion5208 forms a compartment in which electrical cords can be secured.Hand-rail-hook portion 5108 permits the assembly to be carried by handor suspended from the rail of a structure.

The above embodiments of the present invention have been described withrespect to specific features thereof. However, it is noted that thescope of the present invention is defined in the following claims, andshould not be limited by the specific embodiments described above.

1. A monitoring system for use in a breathing circuit, said monitoringsystem being operable to monitor a patient's breathing, said monitoringsystem comprising: a nasal vestibular device comprising a nasalvestibular portion shaped and arranged to be inserted into and retainedwithin a nasal vestibule of the patient without extending past the nasalvestibule towards the trachea of the patient, said nasal vestibularportion having a gas delivery port operable to deliver gas into thenasal vestibule, said nasal vestibular portion having a rigiditysufficient to cause said nasal vestibular portion to stay fixed in andto seal the nasal vestibule when gas is supplied to the nasal vestibulein an amount that causes pressure buildup that is sufficient to preventobstruction of an airway in the patient during depression of at least aportion of the nervous system of the patient; a gas supply tube having afirst end and a second end, said first end being connected to said nasalvestibular device to deliver gas to said nasal vestibular portion foreffusion of the gas into the nasal vestibule via said gas delivery port;and a circuit stethoscope comprising a diaphragm and a t-connectorhaving a first port, a second port and a third port, wherein said firstport of said t-connector is designed to connect with a gas supply lineof the breathing circuit, wherein said second port of said t-connectoris connected to said second end of said gas supply tube, and whereinsaid diaphragm is disposed on said third port of said t-connector. 2.The monitoring system of claim 1, wherein said circuit stethoscopefurther comprises a bell cap, wherein said diaphragm is disposed betweensaid third port of said t-connector and said bell cap, and wherein saidbell cap includes a port for receiving a sound detecting device.
 3. Themonitoring system of claim 2, further comprising a stethoscopetransmitter in communication with said bell cap.
 4. The monitoringsystem of claim 1, wherein said nasal vestibular portion comprises atrimmable portion having raised marks for providing a measuring systemto aid in incrementally trimming said trimmable portion.
 5. Themonitoring system of claim 1, wherein said nasal vestibular portion hasa protruding portion having a diameter larger than a diameter of saidgas supply tube so as to be retained within the nasal vestibule, saidraised marks being located on said protruding portion.
 6. The monitoringsystem of claim 5, wherein said protruding portion comprises a roundedprotruding portion.
 7. The monitoring system of claim 5, wherein saidprotruding portion comprises a bell-shaped protruding portion.
 8. Themonitoring system of claim 1, wherein said nasal vestibular portion hasa protruding portion having a diameter larger than a diameter of saidgas supply tube so as to be retained within the nasal vestibule.